Language: keep original trait method under as alias (#22718)

[PurHur]

Summary

• Zend use T { foo as bar; } aliases — original foo stays callable (method_exists true). The VM/JIT previously renamed (unset the original).
• Fixed in lib/VM.php, lib/JIT.php, and lib/Compiler/TraitComposedMethodResolver.php (php-src-strict; Zend/zend_traits.c).
• Visibility-only as protected unchanged; foo as protected foo2 keeps both.

Closes #22718

Test plan

• Issue repro (Zend + VM):

php /tmp/trait_alias.php; php bin/vm.php /tmp/trait_alias.php
# true / true / 1 1

• php -d memory_limit=512M vendor/bin/phpunit --filter TraitAdaptationTest → OK (9)
• php -d memory_limit=512M vendor/bin/phpunit --filter trait_as_alias → OK (6)
• Related Override/trait filters → OK (56, 12 skipped)

Verification transcript

=== Zend ===
true
true
1 1
=== VM (after fix) ===
true
true
1 1
=== Zend/VM visibility+alias ===
2
true
true

php-src ref: Zend/zend_traits.c trait alias adaptation.

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