Now that the context menu code is on stable, move the sample out of
experimental.
Fixes https://github.com/flutter/samples/issues/2110
## Pre-launch Checklist
- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.
---------
Co-authored-by: Brett Morgan <brett.morgan@gmail.com>
* flutter create
* Copied in from 'contextual-menu-examples' repo
* Works again with the latest updates to the branch
* Clean up anywhere example
* Clean up other examples
* Add to CI
* Updated with release version of context menus, and added platform switcher
* Generated files
* Home icon on your original platform
* Remove web_dashboard from ci, not sure why that change was there...
* Add context_menu to beta channel, but commented out, for the future
* +x permissions on the master script, which I may have accidentally changed before?
* Actual bash comment
* dart format
* Natural default platform'
* A working test, for the email page
* Import order fix
* Test some pages
* More tests
* dart format