Introduce Merge Queue

[frisitano]

Describe the feature

We should consider introducing a merge queue and having sync workflows run when PR's are added to the merge queue such that we can assert that sync is working prior to merging into the target. We already have the sync workflows run upon merge so for now this should be fine but as we converge on a production release and PR velocity increase it may be wise to be defensive and introduce a queue.

Additional context

No response