FR(owlbot): Add support for Github Merge Queues

[parthea]

Currently Owlbot listens to the following Github events, but does not support the Github Queue Event webhook merge_group.checks_requested (See https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#merge_group):

repo-automation-bots/packages/owl-bot/src/owl-bot.ts

Lines 182 to 187 in c3dbbc7

	app.on(
	[
	'pull_request.opened',
	'pull_request.synchronize',
	'pull_request.reopened',
	],

To add support for Github Merge Queues, Owlbot should also listen for the merge_group.checks_requested event

Note: The branch created by the Github Merge Queue will likely be read-only as the branch will be refs/heads/gh-readonly-queue/main/pr-xxxx. We may need to make adjustments so that Owlbot does not attempt to update the branch which is actively in the queue. Instead, owlbot should return success if the diff is empty and fail if the diff is not empty.