[mlir:bytecode] Support lazy loading dynamically isolated regions

We currently only support lazy loading for regions that
statically implement the IsolatedFromAbove trait, but that
limits the amount of operations that can be lazily loaded. This review
lifts that restriction by computing which operations have isolated
regions when numbering, allowing any operation to be lazily loaded
as long as it doesn't use values defined above.

Differential Revision: https://reviews.llvm.org/D156199