Extend api

[micronet24]

Describe the pull request

Along with the PR @gogs/go-gogs-client#124 the REST-API is missing some functionality comparing to the web frontend.

These patches will add some of these functionality, esp:

• Support for modifying a repos
  • description
  • private status
  • listed status
  • default branch
• Updating the list of E-Mails for a given user as admin
• Updating a users Location and website

These are the server-side modifications needed, the client-side adjustments are available in the PR mentioned above.

Checklist

• I agree to follow the Code of Conduct by submitting this pull request.
• I have read and acknowledge the Contributing guide.
• I have added test cases to cover the new code or have provided the test plan.