Improve the output of help, prompts, and so on for `databricks bundle
init` and the default template.
Among other things, this PR adds support for a new `welcome_message`
property that lets a template print a custom message on success:
```
$ databricks bundle init
Template to use [default-python]:
Unique name for this project [my_project]: lennart_project
Include a stub (sample) notebook in 'lennart_project/src': yes
Include a stub (sample) Delta Live Tables pipeline in 'lennart_project/src': yes
Include a stub (sample) Python package in 'lennart_project/src': yes
✨ Your new project has been created in the 'lennart_project' directory!
Please refer to the README.md of your project for further instructions on getting started.
Or read the documentation on Databricks Asset Bundles at https://docs.databricks.com/dev-tools/bundles/index.html.
```
---------
Co-authored-by: shreyas-goenka <88374338+shreyas-goenka@users.noreply.github.com>
## Changes
This PR introduces support for regex pattern validation in our custom
jsonschema validator. This allows us to fail early if a user enters an
invalid value for a field.
For example, now this is what initializing the default template looks
like with an invalid project name:
```
shreyas.goenka@THW32HFW6T bricks % cli bundle init
Template to use [default-python]:
Unique name for this project [my_project]: (_*_)
Error: invalid value for project_name: (_*_). Must consist of letter and underscores only.
```
## Tests
New unit tests and manually.
## Changes
JSON schema properties are a map and thus unordered.
This PR introduces a JSON schema extension field called `order` to allow
template authors to define the order in which template variables should
be resolved/prompted.
## Tests
Unit tests.
---------
Co-authored-by: Pieter Noordhuis <pieter.noordhuis@databricks.com>
Lennart Kats (databricks)
shreyas-goenka