Improve default template (#1046)

## Changes
- Tweak strings, documentation in template
- Extend requirements-dev.txt with setuptools/wheel for building whl
files
- Clarify what the "_job.yml" file is for for users who are only
interested in DLT pipelines (answering a question that came up recently)

## Tests
Existing tests exercise this template

libs/template/templates/default-python/databricks_template_schema.json

@@ -1,10 +1,10 @@
 {
-    "welcome_message": "\nWelcome to the sample Databricks Asset Bundle template! Please enter the following information to initialize your sample DAB.\n",
+    "welcome_message": "\nWelcome to the default Python template for Databricks Asset Bundles!",
     "properties": {
         "project_name": {
             "type": "string",
             "default": "my_project",
-            "description": "Unique name for this project",
+            "description": "Please provide the following details to tailor the template to your preferences.\n\nUnique name for this project",
             "order": 1,
             "pattern": "^[A-Za-z0-9_]+$",
             "pattern_match_failure_message": "Name must consist of letters, numbers, and underscores."
@@ -31,5 +31,5 @@
             "order": 4
         }
     },
-    "success_message": "\n✨ Your new project has been created in the '{{.project_name}}' directory!\n\nPlease refer to the README.md of your project for further instructions on getting started.\nOr read the documentation on Databricks Asset Bundles at https://docs.databricks.com/dev-tools/bundles/index.html."
+    "success_message": "Workspace to use (auto-detected, edit in '{{.project_name}}/databricks.yml'): {{workspace_host}}\n\n✨ Your new project has been created in the '{{.project_name}}' directory!\n\nPlease refer to the README.md file for \"getting started\" instructions.\nSee also the documentation at https://docs.databricks.com/dev-tools/bundles/index.html."
 }

libs/template/templates/default-python/template/{{.project_name}}/.gitignore

@@ -1,4 +1,3 @@
-
 .databricks/
 build/
 dist/

libs/template/templates/default-python/template/{{.project_name}}/README.md.tmpl

@@ -28,7 +28,7 @@ The '{{.project_name}}' project was generated by using the default-python templa
    $ databricks bundle deploy --target prod
    ```
 
-5. To run a job or pipeline, use the "run" comand:
+5. To run a job or pipeline, use the "run" command:
    ```
    $ databricks bundle run
    ```

libs/template/templates/default-python/template/{{.project_name}}/databricks.yml.tmpl

@@ -7,46 +7,36 @@ include:
   - resources/*.yml
 
 targets:
-  # The 'dev' target, used for development purposes.
+  # The 'dev' target, for development purposes. This target is the default.
-  # Whenever a developer deploys using 'dev', they get their own copy.
   dev:
-    # We use 'mode: development' to make sure everything deployed to this target gets a prefix
+    # We use 'mode: development' to indicate this is a personal development copy:
-    # like '[dev my_user_name]'. Setting this mode also disables any schedules and
+    # - Deployed resources get prefixed with '[dev my_user_name]'
-    # automatic triggers for jobs and enables the 'development' mode for Delta Live Tables pipelines.
+    # - Any job schedules and triggers are paused by default
+    # - The 'development' mode is used for Delta Live Tables pipelines
     mode: development
     default: true
     workspace:
       host: {{workspace_host}}
 
-  # Optionally, there could be a 'staging' target here.
+  ## Optionally, there could be a 'staging' target here.
-  # (See Databricks docs on CI/CD at https://docs.databricks.com/dev-tools/bundles/index.html.)
+  ## (See Databricks docs on CI/CD at https://docs.databricks.com/dev-tools/bundles/index.html.)
   #
   # staging:
-  #  workspace:
+  #   workspace:
-  #    host: {{workspace_host}}
+  #     host: {{workspace_host}}
 
   # The 'prod' target, used for production deployment.
   prod:
-    # For production deployments, we only have a single copy, so we override the
+    # We use 'mode: production' to indicate this is a production deployment.
-    # workspace.root_path default of
+    # Doing so enables strict verification of the settings below.
-    # /Users/${workspace.current_user.userName}/.bundle/${bundle.target}/${bundle.name}
-    # to a path that is not specific to the current user.
-    {{- /*
-    Explaining 'mode: production' isn't as pressing as explaining 'mode: development'.
-    As we already talked about the other mode above, users can just
-    look at documentation or ask the assistant about 'mode: production'.
-    #
-    # By making use of 'mode: production' we enable strict checks
-    # to make sure we have correctly configured this target.
-    */}}
     mode: production
     workspace:
       host: {{workspace_host}}
+      # We only have a single deployment copy for production, so we use a shared path.
       root_path: /Shared/.bundle/prod/${bundle.name}
     {{- if not is_service_principal}}
     run_as:
-      # This runs as {{user_name}} in production. Alternatively,
+      # This runs as {{user_name}} in production. We could also use a service principal here
-      # a service principal could be used here using service_principal_name
+      # using service_principal_name (see https://docs.databricks.com/dev-tools/bundles/permissions.html).
-      # (see Databricks documentation).
       user_name: {{user_name}}
     {{end -}}

libs/template/templates/default-python/template/{{.project_name}}/requirements-dev.txt.tmpl

@@ -6,6 +6,10 @@
 ## pytest is the default package used for testing
 pytest
 
+## Dependencies for building wheel files
+setuptools
+wheel
+
 ## databricks-connect can be used to run parts of this project locally.
 ## See https://docs.databricks.com/dev-tools/databricks-connect.html.
 ##

libs/template/templates/default-python/template/{{.project_name}}/resources/{{.project_name}}_job.yml.tmpl

@@ -1,10 +1,17 @@
-# The main job for {{.project_name}}
+# The main job for {{.project_name}}.
+
+{{- /* Clarify what this job is for for DLT-only users. */}}
+{{if and (eq .include_dlt "yes") (and (eq .include_notebook "no") (eq .include_python "no")) -}}
+# This job runs {{.project_name}}_pipeline on a schedule.
+{{end -}}
+
 resources:
   jobs:
     {{.project_name}}_job:
       name: {{.project_name}}_job
 
       schedule:
+        # Run every day at 8:37 AM
         quartz_cron_expression: '44 37 8 * * ?'
         timezone_id: Europe/Amsterdam