Shape inference: GatherBlockQuantized dispatcher (#23748)
### Description
Add shape infer dispatcher for `GatherBlockQuantized` contrib op. It
reuses the dispatcher for `Gather` op since the first two inputs have
the same specs. The output elem type comes from input 2 (scales) for
`GatherBlockQuantized`.
### Motivation and Context
Support shape inference for models with `GatherBlockQuantized` op.
