* Implement optimize send in yjit

This successfully makes all our benchmarks exit way less for optimize send reasons.
It makes some benchmarks faster, but not by as much as I'd like. I think this implementation
works, but there are definitely more optimial arrangements. For example, what if we compiled
send to a jump table? That seems like perhaps the most optimal we could do, but not obvious (to me)
how to implement give our current setup.

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* Attempt at fixing the issues raised by @XrXr

* fix allowlist

* returns 0 instead of nil when not found

* remove comment about encoding exception

* Fix up c changes

* Update assert

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* get rid of unneeded code and fix the flags

* Apply suggestions from code review

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* rename and fix typo

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>