stdlib: request_parse_body() forward-profile builtin

[PurHur]

Closes #16927.

Summary

• Add PHP 8.4 request_parse_body() + RequestParseBodyException forward-profile support.
• VM implementation parses application/x-www-form-urlencoded + multipart/form-data (PHP-in-PHP), no new runtime/ C.
• Add JIT/AOT lowering via nested helper bridge (RequestParseBodyJitHelper) so the builtin runs on native AOT.

Verification (Docker)

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && PHP_COMPILER_PROFILE=8.4 php bin/vm.php test/repro/maintainer_gap_request_parse_body_urlencoded_profile_84.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && PHP_COMPILER_PROFILE=8.4 php bin/vm.php test/repro/maintainer_gap_request_parse_body_multipart_profile_84.php'

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && PHP_COMPILER_PROFILE=8.4 php bin/compile.php -l test/repro/maintainer_gap_request_parse_body_urlencoded_profile_84.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && PHP_COMPILER_PROFILE=8.4 php bin/compile.php -l test/repro/maintainer_gap_request_parse_body_multipart_profile_84.php'

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter "request_parse_body" test/compliance/VMTest.php test/aot/AotTest.php'

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php script/capability-matrix.php && php script/generate-pages-capability-comparison.php'

Made with Cursor