ScrollCapture: Ignore canReceiveKeys when given a specific task ID

Previously if you requested scroll capture on a given task ID, it would
bail out if the window's canReceiveKeys returned false. This change
ignores canReceiveKeys when the task ID is provided and adds tests for
both behaviors.

Bug: 179784589
Test: atest DisplayContentTests
Change-Id: I326384f97a445b72820333b2e26bc466d79f701f