Implemented Tag functions and APIs (no permission checking yet)

[VictorAKang]

Proposed Changes

• Implemented the tag functionality and corresponding APIs
• Changed the update tag API to be a PUT instead of a PATCH
• Missing functions to check overall permissions given by tag
• Missing view to reduce table querying
• Get all tags for a course does not currently allow for nested request (tag having their parent tags within themselves) as I would like to add a view to avoid unnecessary recomputation
• Missing e2e tests