641320fe

By: ValentinHirschi <valentin.hirschi@gmail.com>

add feynkit tensor reduction mode

Add a new numerator tensor reduction mode (similar to how there are multiple modes available for the scalar loop reduction, i.e. alphaloop, MATAD, etc..) called `feynkit` which uses the existing new tensor reducer in feynkit to implement a FORM-less alternative to the current way numerator reduction is performed in `vakint`.

Implement acceptance tests that compare both reduction modes for a multitude of high-rank numerators at various loop counts to strongly establish parity between the two modes (call the original FOMR-based mode `alphaloop` ). Also report runtime performance along with parity in your final summary upon completion.

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