Add Sequence Operators

[TedThemistokleous]

Add sequence operator support for Onnx OPs

Initial work started for SplittToSequence in #1366

Need to support other sequence type ops

[TedThemistokleous]

@pfultz2 I think sequences are just multi input args here?

Likely worth a discussion to support this for the Onnx spec

Looks like we have reverse Sequence implemented already , likely not bad to add others