[RISCV][ISel] Add codegen support for the experimental zabha extension (#80192)

This patch implements the codegen support of zabha (Byte and Halfword
Atomic Memory Operations) v1.0-rc1 extension.
See also https://github.com/riscv/riscv-zabha/blob/v1.0-rc1/zabha.adoc

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Co-authored-by: Craig Topper <craig.topper@sifive.com>