[VITISAI] add float16 and bfloat16 support (#17438)
### Description
Add float16 and bfloat16 data type support for VitisAI ep
### Motivation and Context
The VitisAI ep has added the bfloat datatype support. So we would like
to register the datatype from onnxruntime side to enable them.
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Signed-off-by: Yiming Hu <yiming.hu@amd.com>
