Change dropdowns in Admin / General / Visibility and Access control to be radio buttons

Issue

The dropdowns in the Admin / General / Visibility and Access control section are unnecessary, do not aid in usability, and are not accessible. As well it hides the setting header as the dropdown pops up instead of down from the selection point.

Default branch protection	Default project creation protection

Proposal

Convert these dropdowns to radio buttons.

Default branch protection

• Not protected
  • Both developers and maintainers can push new commits, force push, or delete the branch.
• Protected against pushes
  • Developers cannot push new commits, but are allowed to accept merge requests to the branch. Maintainers can push to the branch.
• Partially protected
  • Both developers and maintainers can push new commits, but cannot force push or delete the branch.
• Fully protected
  • Developers cannot push new commits, but maintainers can. No one can force push or delete the branch.

Default project creation protection

• No one
  • Projects cannot be created.
• Maintainers
  • Only maintainers can create projects.
• Maintainers + Developers
  • Both maintainers and developers can create projects.

Availability & Testing

Please run the package-and-qa job to ensure all end-to-end tests are fine.