[RTG][Elaboration] Support sequences (#7969)

* Simplify materializer to work on only one basic block
* Remove unused addWorklist argument and use a class field instead
* Because the way invocations are elaborated has changed, we don't need the worklist anymore within sequences or tests (we can just iterate over the operations since it's not a graph region), this is a big performance benefit in large tests/sequences.
* Do a BFS over the sequence invocation hierarchy such that callees are only elaborated when all parents are elaborated (because only the `sequence_closure` operation should fix the randomization within a sequence, thus they create a clone before elaborating the referenced sequence)
* Inline all sequences and remove them.