chore: add /v1/models/hub endpoint

[vansangpfiev]

Describe Your Changes

This pull request includes changes to the Models class in the engine/controllers/models.cc and engine/controllers/models.h files. The main focus of these changes is to refactor the ListModel method and introduce a new GetRepositoryList method.

Refactoring and new method introduction:

• engine/controllers/models.cc: Refactored the ListModel method to remove the author parameter and its associated logic.
• engine/controllers/models.cc: Added a new GetRepositoryList method to handle repository listing, including optional author parameter handling.

Updates to method declarations in the header file:

• engine/controllers/models.h: Updated the ListModel method declaration to match the refactored implementation without the author parameter.
• engine/controllers/models.h: Added the new GetRepositoryList method declaration.

Routing changes:

• engine/controllers/models.h: Updated the route for ListModel to remove the author query parameter.
• engine/controllers/models.h: Added a new route for GetRepositoryList with an optional author query parameter.

Fixes Issues

• Closes #
• Closes #

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed