Finish core IR definition, parsing, and write to .dot graph

This MR finishes the core IR definition and parsing. Prototype serializing to .dot graph for visualizing. Parallel matmul example.

requested review from @aaronjc4

assigned to @rarbore2

added 1 commit

• 17ff4e85 - Control token has explicit list of thread spawn factors

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• 5895381e - Add rem/lte/gt/gte ops

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• 0c722d6e - Restructure binary / unary ops to one node type

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• 212d9343 - Add some comments

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mentioned in commit 133a9c9c

merged