[QNN EP] Lower Gemm with 2d bias to FC + ElementwiseAdd when targeting HTP. (#25605)
### Description
Lower Gemm with 2d bias to FC + ElementwiseAdd when targeting HTP.
### Motivation and Context
This change will allow Gemm with 2d bias stays on HTP and not falling back to CPU.
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Signed-off-by: Mu-Chein Hsu <quic_muchhsu@quicinc.com>