Added a tool to quantize Gather to GatherBlockQuantized (#21697)

### Description
Added code in MatMul4BitsQuantizer to quantize Gather to
GatherBlockQuantized.

Only Gather with constant data is quantized.

Since quantized data is in int4, the quantized model will force upgrade
to onnx opset 21.

The implementation purely relies on numpy. If optimization is needed,
C++ kernels can be added later.

Only support default RTN algorithm since GatherBlockQuantized require
zero points to have the same type as quantized data.

### Motivation and Context
Support quantizing gather to int4 in Web scenario.