v0.0.0-6466-gef2bd29a6

[mlir][xls] Optimize ternary_ops::FromKnownBits()

On workloads with large bits datatypes this function has been observed to be super hot (dominating in
the profile).

In 120s of CPU time in this benchmark, 53s comes directly from this function. After optimization
the function takes 500ms.

PiperOrigin-RevId: 701531383