[flang][HLFIR] Adapt OptimizedBufferization to run on all top level ops (#92898)

This means that this pass will also run on hlfir elemental operations
which are not inside of functions.

See RFC:

https://discourse.llvm.org/t/rfc-add-an-interface-for-top-level-container-operations

Some of the changes are from moving the declaration and definition of
the constructor into tablegen (as requested during code review of
another pass).