Update EXTRA_CHOOSER_MODIFY_SHARE_ACTION to use ChooserAction

This allows the app to control the string for this bit of UI (instead of
relying on the system to have a description that applies to all apps),
based upon 1p feedback.

See CTS test added in this topic.

Bug: 272008339
Test: atest CtsSharesheetDeviceTest
Change-Id: Ibe20d998cedd6e56dd14a45cae2b1f17cc2cf65d