Added support for int64 in Slice

Context

The current slice kernel does not support int64 datatypes. An int64 template was missing in the registery.

Concerned file: Line 98 of SliceImpl_kernels.cpp

This problem arose while working on ViT (Vision Transformer) graph, no issues were created for it.

Modified files

(Summarize the changes you made for each modified file - example:

• SliceImpl_kernels.cpp add int64 template in the registery.

Detailed major modifications

No major modifications

TODO

(List the changes that need to be done to track the progress of the MR, you need to update the list when committing !)

• NOT DONE
• DONE
• TO DO