[IR] Dead code elimination pass

[justinchuby]

Eliminate the unused nodes from the graph. An unused node is a node whose outputs are not used by other nodes, and are not part of the graph outputs.

[aishwaryavenkatesan]

Hi @justinchuby , can I work on this issue? I'm pretty new to open source contribution and ready to learn and solve the issues!

[justinchuby]

@aishwaryavenkatesan Thank you! This issue is being worked on. I recommend taking a look at #1432 if you are interested.

[justinchuby]

Done