[GFX1250][MX GEMM] Unified FLATMM GroupedGemm Implementation
for MX Data Types (#8325)
## Motivation
Design and test a unified FLATMM GroupedGemm interface so that it
supports all MX FP8, FP6, and FP4 data types on both the gfx950 and
gfx1250 architectures and works seamlessly across these platforms.
## Technical Details
Implementation exposes Grouped Gemm interface for MX FLATMM and MX TDM
FLATMM pipelines.
## Test Plan
Add the following tests:
- ck_tile/grouped_gemm_mx/test_grouped_gemm_mx_flatmm_non_tdm.cpp
- ck_tile/grouped_gemm_mx/test_grouped_gemm_mx_flatmm_tdm.cpp
- ck_tile/flatmm/test_mx_flatmm_persistent.cpp
Verify on the gfx950 and gfx1250 architectures.
## Test Result
All tests pass. Verified on A0 hardware with rocm-7.14.0a20260517
## Submission Checklist
- [x] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.
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