Add supermirror efficiency function based on lookup table

[astellhorn]

At the moment, the supermirror efficiency is read into the workflow as a polynomial function with pre-defined parameters. It would be nice to insert another possibility: a supermirror-efficiency(lambda) lookup table that has been acquired from commissioning beamtimes. This will be a table with following entries: x=lambda, y=efficieny, z=efficiency_error (as in the attached example). My request then would include following steps:

(i) aside the current possibility of defining a supermirror polynomial in the workflow, insert additionally the possibility of loading a supermirror-efficiency Lookup table. Currently, calling pol.supermirror.SupermirrorWorkflow() automatically calls the class "SecondDegreePolynomialEfficiency", which is by default based on the polynomial expression. Hence, this has to be divided up into two possibilities, e.g. something like "SecondDegreePolynomialEfficiency" & "EfficiencyLookupTable"

(ii) The Efficiency Lookup tables from commissioning times have to be available for the users in scipp. Here I am attaching an example of a supermirror polarizer from ZOOM @ ISIS that we can use to test our workflow - it would be nice if that can be uploaded for the tests already:

f_drabkin_reb.csv