Add "edit_source" extra to screenshot/clipboard edit intents

Allows logging of entrance source in Markup. Also changes the
clipboard extra syntax from a boolean to a string (matching
existing implementation in sharesheet).

Bug: 286389315
Test: integration test with markup (requires cl/552491695)
Test: atest ActionIntentCreatorTest, IntentCreatorTest

Change-Id: If98b2cdfff779e422b3a00f402ade112f0aa04dc