See this PR thread. The logic for collation on views is slightly different than collation on non-views since a user can specify a custom collation on a collection that doesn't match the collection's default collation but a user cannot specify a collation on a view that doesn't match the view's default collation.

The view-specific error-checking happens here but the final collation is set here when creating the resolved view aggregate request. We should try to put all this logic in one place so the collation-on-views logic is easier to understand.