R1:18757e43de2b

Allow entire dashboards to be copied

Summary:
Further improve UX for dealing with policy rules on dashboards:

- When in the "Manage" view of a dashboard you can not edit:
- Don't show the panel management controls.
- Show a notice that the board isn't editable, recommending you make a copy instead.
- Add a "Copy Dashboard" action to create a copy which you //can// edit.

Test Plan: Copied some dashboards. See screenshots.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley…