refactor: message and useridentityaction classes

[vgupta98]

Description

This PR moves TrackEvent, GroupEvent and ScreenEvent classes to new files. It also moves SetAnonymousIdAction class to a new file.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactor/optimization

Implementation Details

Checklist

• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation (if appropriate).
• I have ensured that my code follows the project's code style.
• I have checked for potential performance impacts and optimized if necessary.
• I have checked the code for security issues.
• I have updated the changelog (if required).

How to test?

Breaking Changes

Maintainers Checklist

• The code has been reviewed.
• CI tests have passed.
• All necessary documentation has been updated.

Screenshots (if applicable)

Additional Context

[saikumarrs]

LGTM