[SVE] Break dependency of Type.h on DerivedTypes.h

Summary:
Inline functions in Type.h depended upon inline functions isVectorTy and
getScalarType defined in DerivedTypes.h. Reimplement these functions in
Type.h in terms of Type

Reviewers: rengolin, efriedma, echristo, c-rhodes, david-arm

Reviewed By: echristo

Subscribers: tschuett, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81684