feat(workflow): Backfill ProjectTeam model

[macqueen]

part 2/3, depends on #6136

cc @getsentry/workflow

[ghost]

	2 Warnings
⚠️	You should update CHANGES due to the size of this PR
⚠️	PR includes migrations

Migration Checklist

• new columns need to be nullable (unless table is new)
• migration with any new index needs to be done concurrently
• data migrations should not be done inside a transaction
• before merging, check to make sure there aren't conflicting migration ids

Generated by 🚫 danger

[dcramer]

reminder to deploy part 1 before deploying part 2

[mattrobenolt]

We doing this? This is in my review queue even though it's been approved. :)

[macqueen]

@mattrobenolt i was gonna wait until part 3 (where we actually use the new fields) is closer to being done. i can kick you off as a reviewer