This patch moves the part of operation verifiers dependent on the
contents of their regions to the corresponding `verifyRegions` method.
This ensures these are only triggered after the operations in the region
have themselved already been verified in advance, avoiding checks based
on invalid nested operations.
The `LoopWrapperInterface` is also updated so that its verifier runs
after operations in the region of ops with this interface have already
been verified.
4091bc61e3