Add property ci_default_git_depth to both Project.cs and ProjectUpdate.cs

[matt-pan]

This property can be set via PUT update on projects and is part of the Project response

[matt-pan]

Oh, I didn't know this is tested against the public API
Should be fine though, as this parameter is in https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/api/openapi/openapi_v2.yaml on the GET /api/v4/projects/{id} as well as the PUT /api/v4/projects/{id}

[louis-z]

Thanks for your contribution, @matt-pan.

In order to get this PR merged quickly,

• Address the inline comments, and
• Update the declared public API. This can easily be done via VS2022's "Quick Actions and Refactorings" (when asked "Fix all occurrences in:", make sure to select "Solution"):