Make ClassGroup intrinsic compatible with original classgroup function

[koffie]

We need to make our classgroup function a drop in replacement for the original one from: https://magma.maths.usyd.edu.au/magma/handbook/text/514#5800

I.e. the signature:

CurveArith/src/classgroup.m

Line 423 in 612fcf7

intrinsic ClassGroup(F::FldFun : BaseDivisor := false) -> GrpAb

Should become

ClassGroup(F : parameters) : FldFun -> GrpAb, Map, Map

[koffie]

Once this is fixed the test:

CurveArith/tests/src/test_classgroup.m

Line 1 in 7c0094f

procedure TestClassGroupCrv()

can be enabled. The test now fails because of this