ZJIT: Annotate Kernel#frozen? as returning BoolExact #54

Job	Run time
cargo clippy	41s
make (zjit-bindgen, To fix: use patch in logs, --enable-zjit=dev --with-gcc=clang-16, /usr/bin/cl...	4m 53s
make (check, --zjit-disable-hir-opt --zjit-call-threshold=1, -T --zjit-disable-hir-opt -T --zjit-...	16m 6s
make (test-bundled-gems, --enable-zjit=dev, --zjit-call-threshold=1)	21m 10s
make (zjit-check, --enable-yjit --enable-zjit=dev, 1.85.0)	4m 51s
make (check, --zjit-call-threshold=1, -T --zjit-call-threshold=1, --enable-zjit=dev, --seed=39471)	20m 16s
ZJIT Ubuntu result	2s
	1h 7m 59s

Provide feedback