Add callback to ImageActionUtils for unresolved intents

Adding an optional callback to ImageActionUtils.persistBitmapAndStartActivity allows for external handling of the case in which the given intent cannot be resolved. The main use case is for NIU Actions when the user has chosen an assistant that does not support the feature. TaskOverlayFactoryGo provides a callback that shows a dialog in this case.

Various parts of TaskOverlayFactoryGo were also made public for better testability.

Bug: 196125662
Bug: 192406446
Bug: 195681795
Test: m -j RunLauncherGoGoogleRoboTests ROBOTEST_FILTER=TaskOverlayFactoryGoTest
Change-Id: I64f3a1274bc942a64e964dca20bd4245e336ad9d