Previously we essentially never freed block even after invalidation.
Their reference count never reached zero for a couple of reasons:
1. `Branch::block` formed a cycle with the block holding the branch
2. Strong count on a branch that has ever contained a stub never
   reached 0 because we increment the `.clone()` call for
   `BranchRef::into_raw()` didn't have a matching decrement.

It's not safe to immediately deallocate blocks during
invalidation since `branch_stub_hit()` can end up
running with a branch pointer from an invalidated branch.
To plug the leaks, we wait until code GC or global invalidation and
deallocate the blocks for iseqs that are definitely not running.

When we run global invalidation for TracePoints or code GC, we clear out
all blocks in our assumptions table but we don't deallocate the backing
buffers. Let's reclaim some memory during these rare events.

YJIT: Skip padding jumps to side exits

Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com>
Co-authored-by: Alan Wu <alansi.xingwu@shopify.com>

Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com>
Co-authored-by: Alan Wu <alansi.xingwu@shopify.com>

* YJIT: Stop wrapping CmePtr with CmeDependency

* YJIT: Fix an outdated comment [ci skip]

Co-authored-by: Alan Wu <alansi.xingwu@shopify.com>

Co-authored-by: Alan Wu <alansi.xingwu@shopify.com>

We switch to a new page when we detect dropped_bytes flipping from false
to true. Previously, when we patch code for invalidation during code gc,
we start with the flag being set to true, so we failed to apply patches
that straddle pages. We would write out jumps half way and then stop,
which left the code corrupted.

Reset the flag before patching so we patch across pages properly.

* YJIT: Count freed ISEQs

* YJIT: Avoid creating payloads for non-JITed ISEQs