feat(moose): Phase A + Phase C-mini — HasCompiler stub + Class::MOP shim

[fglock]

Summary

Implements the next phases of dev/modules/moose_support.md:

• Phase A — deterministic ExtUtils::HasCompiler stub
  (src/main/perl/lib/ExtUtils/HasCompiler.pm). Always reports "no
  compiler", instead of relying on $Config{usedl} happening to be
  empty.
• Phase C-mini — Class::MOP shim (src/main/perl/lib/Class/MOP.pm)
  with class_of, get_metaclass_by_name, store_metaclass_by_name,
  remove_metaclass_by_name, does_metaclass_exist,
  get_all_metaclasses (and friends), get_code_info (via B),
  is_class_loaded, load_class, load_first_existing_class. Returns
  "no metaclass" everywhere — the correct answer under the
  Moose-as-Moo shim.

The previous behavior was a hard Undefined subroutine &Class::MOP::class_of called the moment Moo's _Utils::_load_module
hit a not-installed dependency on a class that already had Moose.pm
loaded (which our shim arranges at startup, by design).

Also updates dev/modules/moose_support.md with:

• A new column in the baseline table reflecting the post-refcount/DESTROY
  state (was missing — the headline numbers had drifted from ~29 /
  370 / 246 to 35 / 372 / 244).
• A third column for this PR's results.
• Phase A / Phase C-mini marked done in the progress tracker.

Effect on ./jcpan -t Moose (Moose 2.4000)

Metric	Before	After
Files executed	478	478
Assertions executed	616	667
Fully passing files	35	36
Partially passing files	94	98
Compile/load fail (no tests)	349	344
Assertions ok	372	419
Assertions fail	244	248

Net: +51 assertions executed, +47 newly pass, +1 fully-green file.
The four extra "failures" are upstream tests that previously bailed
before reaching their assertion phase and now reach it; none are
real regressions.

Test plan

• make — full unit suite passes (no regressions on either
  backend).
• ./jperl -MExtUtils::HasCompiler=can_compile_loadable_object -e 'print can_compile_loadable_object(quiet=>1) ? "yes" : "no"'
  → no.
• ./jperl -MClass::MOP -e 'print Class::MOP::class_of("NoSuch") // "undef"' → undef.
• ./jperl -MClass::MOP -e 'print join(" ", Class::MOP::get_code_info(\&Class::MOP::class_of))'
  → Class::MOP class_of.
• ./jperl -MMoose -e 'package P { use Moose; has x => (is=>"rw") }; print P->new(x=>42)->x' → 42.
• ./jcpan -t Moose — numbers above; saved in
  /tmp/moose_test2.txt.

What's intentionally not in this PR

• Phase B (strip XS keys in WriteMakefile). Not yet needed because
  we're not yet trying to install upstream Moose.
• Phase C-full / Phase D (real Class::MOP::Class instances, port
  of pure-Perl Moose). Tracked in the design doc; would unblock another
  big chunk of failing tests but is a much larger effort.

Generated with Devin

[fglock]

Superseded by #572, which includes both commits (Phase A + C-mini and Phase 2 stubs) plus the Phase-3+ planning update.