[mlir][SPIRV] Add named-barrier type and OpNamedBarrierInitialize / OpMemoryNamedBarrier (#195664)
Adds the SPIR-V named-barrier object (TypeNamedBarrier) along with
NamedBarrierInitialize and MemoryNamedBarrier ops, gated on the
NamedBarrier capability and SPIR-V 1.1+.
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Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>