This reverts commit 8c44abc0.

Text editing shortcuts involving the arrow keys are no longer handled by RenderEditable's RawKeyboardListener, they use the new Shortcuts setup.  First PR in a plan to port all text editing keyboard handling to shortcuts.

Now that ShaderMask works on web, enable it for CupertinoContextMenu and unskip relevant tests.

* Adds set text semantics action to render editable

* addressing comments

* re-enable test

* fix test

* fix more test

* fix bad merge

* addressing comment

* update dynamic to Object?

This reverts commit f8cd24de in an attempt to re-land it.

There are no changes in this PR from #74373, since it only failed Google internal tests, and we think that the solution involves updating those tests instead of changing this code.

This reverts commit a46139a2.