## 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.
shreyas-goenka