ComputeFstat: add required SWIG directives

- add directive ARRAY_MULTIPLE_LENGTHS() to suppress warnings when
  numFreqBins and numDetectors are used in multiple arrays in FstatResults
- add ARRAY_1D_PTR_1D() array type to wrap arrays of pointers to arrays,
  such as twoFPerDet and FaFbPerDet in FstatResults
SFTutils-LAL.[ch]: remove from Doxygen and SWIG