[AMD] Improve Scheduling for Async BF16 GEMM

[raikonenfnu]

• Use single AsyncWait (1030 -> 1070)
• Move local load before global load to hide latency (1076)
• Move slice local load(3) to the cluster before dot(3) (1080.5)
• Update clusterBarrier to schedBarrier + s_barrier + schedBarrier (1086)

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[raikonenfnu]

Closing original PR #802 for this one since I wanted to keep a checkpoint on the old branch

[jungpark-mlir]

LGTM!