Add Zabha extension

[ved-rivos]

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Specification: https://github.com/riscv/riscv-zabha

Tested with RISC-V arch. tests and checked against spike.

[github-actions[bot]]

Test Results

712 tests  ±0   712 :white_check_mark: ±0   0s :stopwatch: ±0s   6 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit 19042124. ± Comparison against base commit 40ed0c5b.

:recycle: This comment has been updated with latest results.

[Timmmm]

@billmcspadden-riscv any objection to merging this? I can't see any reason not to.

[Timmmm]

I think this is good to go. I'll merge this in a few days if nobody objects.