P23 adds the official JALR test

P23 widens P22 from twenty-four official tests to twenty-five by adding I-jalr-00.S.

Command:

make -C projects/23_rv32i_jalr_tests/test

Result: PASS

Summary: PASS=25 FAIL=0 NOT RUN=0

No RTL changed. The P22 reference-emulated signature flow was extended from JAL to JALR, and the official self-check accepted the result.

Next target: branch tests.