While working on the Torque compiler, I've sometimes found it difficult
to understand Torque's intermediate representation and how it
corresponds to the output. In this change, I propose adding a build flag
that instructs Torque to emit comments describing its IR, interspersed
in the generated code. This is particularly useful for seeing the stack
management instructions (Peek, Poke, and DeleteRange) which don't emit
any corresponding C++ code.

Bug: v8:7793
Change-Id: I24bdec47da76c9bd751b928d3cd92aa513dc6593
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2748040Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#73352}