feat(dispatcher): add has_backend_impl and expose op name on dispatch wrapper & other updates

[hannahli-nv]

Description

Update codes.

This PR contains 6 new commit(s).

Commits included:

a61cd51 fix(tilecpp): mask the FMHA forward tail store
9741881 fix(cutile): MLA split-KV NaN on sm_80 for non-power-of-2 seqlen
1a15ef4 cuTile ragged_bmm: tune both kernel variants instead of guessing swap_ab from the shape
39cf8d4 fix(tilecpp): chunk_gated_delta_rule V-tile bounds and G/Beta dtype
6493cb3 perf(cutile softmax): per-op approx exp/div in all forward kernels
1496eab feat(dispatcher): add has_backend_impl and expose op name on dispatch wrapper

CI Configuration

config:
  build: true
  # valid options are "ops" and "benchmark"
  test: []

Checklist

• Code formatted and imports sorted via repo specifications (./format.sh)
• Documentation updated (if needed)
• CI configuration reviewed

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[hannahli-nv]

/ok to test 8a72068