New feature: extract related bricks from changed tests 🎉

[DavidVujic]

Adding the possibility to find related bricks for changed tests. There is already an existing feature for finding out which bricks are affected by changes in tests with the poly test diff command. The existing behaviour of this command is to inspect and find affected bricks by the imports in the tests (using AST parsing of the test modules).

This new feature adds a --strategy path option to find the corresponding brick according to the folder structure, regardless if the brick was imported in the test or not. This is useful fo extract bricks that are related (or "owners") of the tests.

Example

A test has changed: test/components/my_namespace/my_brick/the_test_for_the_brick.py.
The poly tool will look for a brick in the same path structure as the test, components/my_namespace/my_brick, when using the new --strategy option.

Usage:

# the default behaviour is strategy by imports, as before
poly test diff

# or (same result as the above)
poly test diff --strategy imports

# the new feature, finding related bricks
poly test diff --strategy path

The idea and suggestions on how to implement it is from a user of Polylith, thank you! ⭐ 🙏

Issue: #459
Implementation details (pull request): #460