[AMDGPU] Mitigate GFX12 VALU read SGPR hazard (#100067)

Any SGPR read by a VALU can potentially obscure SALU writes to the same
register.
Insert s_wait_alu instructions to mitigate the hazard on a

[AMDGPU] Mitigate GFX12 VALU read SGPR hazard (#100067)

Any SGPR read by a VALU can potentially obscure SALU writes to the same
register.
Insert s_wait_alu instructions to mitigate the hazard on affected paths.

Compute a global cache of SGPRs with any VALU reads and use this to
avoid inserting mitigation for SGPRs never accessed by VALUs.

To avoid excessive search when compile time is priority implement
secondary mode where all SALU writes are mitigated.

Co-authored-by: Shilei Tian <shilei.tian@amd.com>

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