Migrations: Detect primary key property renames

[bricelam]

Similar to #5155 (but perhaps not as useful), we could also detect renamed properties that are part of the primary key if...

1. The number of primary key properties are the same, and
2. The would-be-added property is in the same position as a would-be-removed property

[bricelam]

I need to think about it more, but my initial feeling is that it becomes even less useful for alternate keys, and indices.

[bricelam]

Also, I wonder if just doing structural matching (e.g. everything is the same except the name) would cover all these cases for much cheaper.

[divega]

Triage: we want to have a design discussion about this, including @rowanmiller.

[bricelam]

Closing in favor of doing #6582 instead.