This PR implements `verify-diagnostics=only-expected` which is a "best
effort" verification - i.e., `unexpected`s and `near-misses` will not be
considered failures. The purpose is to enable narrowly scoped checking
of verification remarks (just as we have for lit where only a subset of
lines get `CHECK`ed).
Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
I'm not touching PointerUnion::dyn_cast for now because it's a bit
complicated; we could blindly migrate it to dyn_cast_if_present, but
we should probably use dyn_cast when the operand is known to be
non-null.
Transform dialect interpreter is designed to be usable outside of the
pass pipeline, as the main program transformation driver, e.g., for
languages with explicit schedules. Provide an example of such usage with
a couple of tests.
