Refactor: Make`git_provider` params non-optional when possible

[malhotra5]

What problem or use case are you trying to solve?
Many parts of the codebase do not require information on git_provider. As a result, the codebase have logic that checks all the provider services even though in reality we always pass a git_provider

A good example of this would be the search_repository to get_paginated_repositories methods in the ProviderHandler

Describe the UX or technical implementation you have in mind

We should make git_provider require throughout the entire codebase.

The only exception being the start new conversation API endpoint, which should have optional git_provider param so that OH API users can start conversations more conveniently with just a repo name. If a name baed collision were to occur across providers, we should throw an error requesting git_provider information as well.

Additional context

If you find this feature request or enhancement useful, make sure to add a 👍 to the issue