[WIP] feat: add filters implementation P1

[mariajgrimaldi]

Description:
This PR adds filters for the following processes:

• Login
• Registration
• Enrollment
• Un-enrollment

Dependencies:
The implementation uses the tooling defined in #1

Testing instructions:

1. Open page A
2. Do thing B
3. Expect C to happen
4. If D happened instead - check failed.

Reviewers:

• tag reviewer
• tag reviewer

Merge checklist:

• All reviewers approved
• CI build is green
• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed

Post merge:

• Create a tag
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)

Author concerns:

• Folder structure, is this what we want? : from openedx_filters.lms.auth.v1.login import before_creation as pre_login_filter
• Filter naming: before_creation? we'd have to always import like this: from ... import before_creation as CONTEXT_NAME

[mariajgrimaldi]

any comments so far? @felipemontoya