Add permission check when creating PR (#31033)

user should be a collaborator of the base repo to create a PR

options/locale/locale_en-US.ini

@@ -1765,6 +1765,7 @@ compare.compare_head = compare
 pulls.desc = Enable pull requests and code reviews.
 pulls.new = New Pull Request
 pulls.new.blocked_user = Cannot create pull request because you are blocked by the repository owner.
+pulls.new.must_collaborator = You must be a collaborator to create pull request.
 pulls.edit.already_changed = Unable to save changes to the pull request. It appears the content has already been changed by another user. Please refresh the page and try editing again to avoid overwriting their changes
 pulls.view = View Pull Request
 pulls.compare_changes = New Pull Request