ZJIT: Make `hir::types::Class` not final and have it include metaclasses #9659

Job	Run time
cargo test	1m 27s
cargo clippy	45s
make (check, --enable-yjit=dev)	12m 52s
make (test-bundled-gems, --enable-yjit=dev)	12m 1s
make (yjit-bindgen, To fix: use patch in logs, --with-gcc=clang-14 --enable-yjit=dev --enable-zji...	5m 43s
make (check, --enable-yjit=dev, --yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc, -T --yj...	13m 17s
make (check, RUSTC='rustc +1.58.0', 1.58.0)	9m 37s
YJIT Ubuntu result	4s
	55m 46s

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