enumerator's meth attribute is an ID, which is not a Ruby object, so we
should not apply the write barrier on it.

Enumerator#zip yields a single array, not multiple arguments,
so Enumerator::Lazy#zip should do the same.

Fixes [#20623]

While working on a separate issue we found that in some cases
`ary_heap_realloc` was being called on frozen arrays. To fix this, this
change does the following:

1) Updates `rb_ary_freeze` to assert the type is an array, return if
already frozen, and shrink the capacity if it is not embedded, shared
or a shared root.
2) Replaces `rb_obj_freeze` with `rb_ary_freeze` when the object is
always an array.
3) In `ary_heap_realloc`, ensure the new capa is set with
`ARY_SET_CAPA`. Previously the change in capa was not set.
4) Adds an assertion to `ary_heap_realloc` that the array is not frozen.

Some of this work was originally done in
https://github.com/ruby/ruby/pull/2640, referencing this issue
https://bugs.ruby-lang.org/issues/16291. There didn't appear to be any
objections to this PR, it appears to have simply lost traction.

The original PR made changes to arrays and strings at the same time,
this PR only does arrays. Also it was old enough that rather than revive
that branch I've made a new one. I added Lourens as co-author in addtion
to Aaron who helped me with this patch.

The original PR made this change for performance reasons, and while
that's still true for this PR, the goal of this PR is to avoid
calling `ary_heap_realloc` on frozen arrays. The capacity should be
shrunk _before_ the array is frozen, not after.

Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
Co-Authored-By: methodmissing <lourens@methodmissing.com>

This `st_table` is used to both mark and pin classes
defined from the C API. But `vm->mark_object_ary` already
does both much more efficiently.

Currently a Ruby process starts with 252 rooted classes,
which uses `7224B` in an `st_table` or `2016B` in an `RArray`.

So a baseline of 5kB saved, but since `mark_object_ary` is
preallocated with `1024` slots but only use `405` of them,
it's a net `7kB` save.

`vm->mark_object_ary` is also being refactored.

Prior to this changes, `mark_object_ary` was a regular `RArray`, but
since this allows for references to be moved, it was marked a second
time from `rb_vm_mark()` to pin these objects.

This has the detrimental effect of marking these references on every
minors even though it's a mostly append only list.

But using a custom TypedData we can save from having to mark
all the references on minor GC runs.

Addtionally, immediate values are now ignored and not appended
to `vm->mark_object_ary` as it's just wasted space.

enumerator_block_call was not safe for compaction because the Array
backing the argv was not pinned, so it could get moved during compaction
which would make argv point to somewhere else.

The test crashes when RGENGC_CHECK_MODE is turned on:

    TestEnumerator#test_with_index_under_gc_compact_stress
    check_rvalue_consistency: 0x55db0b399450 is not a Ruby object.
    test/ruby/test_enumerator.rb:133: [BUG] check_rvalue_consistency_force: there is 1 errors.
    ruby 3.3.0dev (2023-12-23T23:00:27Z master 50bf437341) [x86_64-linux]
    -- Control frame information -----------------------------------------------
    c:0034 p:---- s:0192 e:000187 CFUNC  :with_index
    c:0033 p:---- s:0185 e:000184 CFUNC  :each
    c:0032 p:---- s:0182 e:000181 CFUNC  :to_a
    c:0031 p:0055 s:0178 e:000175 BLOCK  test/ruby/test_enumerator.rb:133
    c:0030 p:0024 s:0172 e:000171 METHOD tool/lib/envutil.rb:242
    c:0029 p:0024 s:0167 e:000166 METHOD tool/lib/envutil.rb:251
    c:0028 p:0005 s:0160 e:000159 METHOD test/ruby/test_enumerator.rb:131
    ...
    -- C level backtrace information -------------------------------------------
    build/ruby(rb_print_backtrace+0x14) [0x55db0b1deb21] vm_dump.c:820
    build/ruby(rb_vm_bugreport) vm_dump.c:1151
    build/ruby(bug_report_end+0x0) [0x55db0b3a53a6] error.c:1042
    build/ruby(rb_bug_without_die) error.c:1042
    build/ruby(die+0x0) [0x55db0afc77c2] error.c:1050
    build/ruby(rb_bug) error.c:1052
    build/ruby(gc_move+0x0) [0x55db0afbada0] gc.c:1714
    build/ruby(check_rvalue_consistency+0xa) [0x55db0afef0c3] gc.c:1729
    build/ruby(is_markable_object) gc.c:4769
    build/ruby(gc_mark_stack_values) gc.c:6595
    build/ruby(rb_gc_mark_vm_stack_values) gc.c:6605
    build/ruby(rb_execution_context_mark+0x39) [0x55db0b1d8589] vm.c:3309
    build/ruby(thread_mark+0x15) [0x55db0b1a9805] vm.c:3381
    build/ruby(gc_mark_stacked_objects+0x6d) [0x55db0aff2c3d] gc.c:7564
    build/ruby(gc_mark_stacked_objects_all) gc.c:7602
    build/ruby(gc_marks_rest) gc.c:8797
    build/ruby(gc_marks+0xd) [0x55db0aff43d5] gc.c:8855
    build/ruby(gc_start) gc.c:9608
    build/ruby(rb_multi_ractor_p+0x0) [0x55db0aff5463] gc.c:9489
    build/ruby(rb_vm_lock_leave) vm_sync.h:92
    build/ruby(garbage_collect) gc.c:9491
    build/ruby(newobj_slowpath+0xcb) [0x55db0aff57ab] gc.c:2871
    build/ruby(newobj_slowpath_wb_protected) gc.c:2895
    build/ruby(newobj_of0+0x24) [0x55db0aff59e4] gc.c:2937
    build/ruby(newobj_of) gc.c:2947
    build/ruby(rb_wb_protected_newobj_of) gc.c:2962
    build/ruby(ary_alloc_embed+0x10) [0x55db0b2f3e40] array.c:668
    build/ruby(ary_new) array.c:709
    build/ruby(rb_ary_tmp_new_from_values) array.c:759
    build/ruby(rb_ary_new_from_values) array.c:771
    build/ruby(args_copy+0x18) [0x55db0b1bbb88] vm_args.c:158

Instead of `RUBY_REFERENCES_START` and `RUBY_REFERENCES_END`, so that
auto-indent works well.

Also move `struct` so that `typedef`-ed names can be used.