Add models for sessions and tracks

[Shivangi-ch]

Fixes #9109

Short description of what this resolves:

Added models for session , tracks and other related models

Changes proposed in this pull request:

• Added models for Tracks , Microlocations, Session, and SessionTypes inside events app.
• Added models for VideoStreams inside video_channels app.

PS - This PR builds on top of work done in PR #9125. Please merge it before merging this PR.

Checklist

• [x] I have read the Contribution & Best practices Guide and my PR follows them.
• [x] My branch is up-to-date with the Upstream development branch.
• [x] The unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation (if appropriate)
• [x] All the functions created/modified in this PR contain relevant docstrings.

[Shivangi-ch]

Please review this PR!

[fillingtothemomo]

@Shivangi-ch this PR has commits of your previous PR as well so you could either squash the commits to not mess up the commit history or use different branches for both PRs I feel.