[SveEmitter] Add builtins for svreinterpret

The reinterpret builtins are generated separately because they
need the cross product of all types, 121 functions in total,
which is inconvenient to specify in the arm_sve.td file.

Reviewers: SjoerdMeijer, efriedma, ctetreau, rengolin

Reviewed By: efriedma

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78756