CV2-2648: migrate tipline requests

[melsawy]

Description

Expose the code for TiplineRequest migration so we can proceed with migration before live deployment.
PR contains:

• The database migration
• Rake task check:migrate:migrate_tipline_requests
• Empty TiplineRequest model:

Also I updated the rake task to accept pre-defined keyword for slug(i.e rails check:migrate:migrate_tipline_requests['slug:custom_slugs]) by this way the rake task will allow user to type team slugs using terminal.

References: CV2-2648

How has this been tested?

Tested locally against live DB using specific team.

Things to pay attention to during code review

Please describe parts of the change that require extra attention during code review, for example:

• File FFFF, line LL: This refactoring does this and this. Is it consistent with how it’s implemented elsewhere?
• Etc.

Checklist

• I have performed a self-review of my own code
• I have added unit and feature tests, if the PR implements a new feature or otherwise would benefit from additional testing
• I have added regression tests, if the PR fixes a bug
• I have added logging, exception reporting, and custom tracing with any additional information required for debugging
• I considered secure coding practices when writing this code. Any security concerns are noted above.
• I have commented my code in hard-to-understand areas, if any
• I have made needed changes to the README
• My changes generate no new warnings
• If I added a third party module, I included a rationale for doing so and followed our current guidelines