Add admin function access controls

[xywang279279-afk]

Closes #1280

Summary

• add a synced host-only toggle for allowing admin functions for all users
• add an admin settings UI toggle and adminfunctions console command
• gate the tilemap editor client-side and server-side as the first admin-only function

Testing

• git diff --check
• Not run: Unity editor/PlayMode tests are not available in this environment

[xywang279279-afk]

Pushed a small compile fix in b62b932 for the missing System namespace in LockLockerInteraction.cs.

The current failing Run Tests job still reports that same pre-existing error because the pull_request_target workflow is checking out the base develop ref (423f1d7) rather than this PR head (b62b932).

[xywang279279-afk]

Hi, just checking whether there is anything I should adjust for this PR. It addresses #1280, and I left a note above about the current CI failure appearing to run against the base develop ref instead of this PR head.