[QNN] ReduceL2 Support (#22636)
Add ReduceL2 support to QNN EP. Some of the QNN AI Hub models contain
Reduce L2, such as openai_clip_CLIPTextEncoder and
openai_clip_CLIPIamgeEncoder, without this PR, the ReduceL2 will be
assigned to CPU and the graph will be split to 2 QNN graphs, which this
PR, all nodes will be in QNN EP.
