Draft: E-ratio algorithm integration [WIP]

Harry Cookerequested to merge
hacooke/athena:21.3-hacooke-eratio into 21.3

Adding E-ratio algorithm to TrigL0GepPerf package. Several helper classes necessary for this to function, so created a new package for these, TrigL0GepUtils. (Currently issues with this -- either the package hasn't been created properly or my CMake leaves room for improvement -- need help getting this to function.)

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