Merge pull request #16300 from jh66637/ste-89-backend

Merge pull request #16300 from jh66637/ste-89-backend

Classes used by Step 89

The purpose of the classes is as follows:

PrecomputedFEEvaluationData stores the values and gradients for all requested points.
PrecomputedFEEvaluationDataView gives a structured access to the values/gradients of a cell/face via get_shift()
FERemoteEvaluationCommunicator fills the values/gradients in data using RPE
FERemoteEvaluation is a class similar to FEEvaluation but accessing precomputed/cached values/gradients in PrecomputedFEEvaluationData. The values/gradients of all points are updated via gather_evaluate(vector, flags). The function reinit() shifts the view to the current cell/face. The functions get_value() and get_gradient() give access to the value/gradient of the specified cell.