[SveEmitter] Add builtins for svdupq and svdupq_lane

* svdupq builtins that duplicate scalars to every quadword of a vector
  are defined using builtins for svld1rq (load and replicate quadword).
* svdupq builtins that duplicate boolean values to fill a predicate vector
  are defined using `svcmpne`.

Reviewers: SjoerdMeijer, efriedma, ctetreau

Reviewed By: efriedma

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78750