Fixes an inconsistency where cloneRegionBefore did not notify the listener of "op insertion" (whereas OpBuilder::clone does). Various parts of the core infrastructure such as the GreedyPatternRewriteDriver depend on such notifications.
Also fixes a bug where no notifications were sent about block creation when cloning IR.
Ops/blocks are notified in such an order in which they could have been created one-by-one with an OpBuilder. This ensures that when a listener is notified about an op being created, it was already notified about the defining ops of the operands (unless there is a block cycle/graph region).
As a consequence, this allows us to use the same cloneRegionBefore implementation in the dialect conversion. This makes it possible to make the function non-virtual and to move this function to the OpBuilder (instead of RewriterBase).
Note: This revision subsumes D144194, D144266 and D144000.
Depends On: D144193