[ARM,CDE] Implement CDE unpredicated Q-register intrinsics

Summary:
This patch implements the following intrinsics:

  uint8x16_t __arm_vcx1q_u8 (int coproc, uint32_t imm);
  T __arm_vcx1qa(int coproc, T acc, uint32_t imm);
  T __arm_vcx2q(int coproc, T n, uint32_t imm);
  uint8x16_t __arm_vcx2q_u8(int coproc, T n, uint32_t imm);
  T __arm_vcx2qa(int coproc, T acc, U n, uint32_t imm);
  T __arm_vcx3q(int coproc, T n, U m, uint32_t imm);
  uint8x16_t __arm_vcx3q_u8(int coproc, T n, U m, uint32_t imm);
  T __arm_vcx3qa(int coproc, T acc, U n, V m, uint32_t imm);

Most of them are polymorphic. Furthermore, some intrinsics are
polymorphic by 2 or 3 parameter types, such polymorphism is not
supported by the existing MVE/CDE tablegen backends, also we don't
really want to have a combinatorial explosion caused by 1000 different
combinations of 3 vector types. Because of this some intrinsics are
implemented as macros involving a cast of the polymorphic arguments to
uint8x16_t.

The IR intrinsics are even more restricted in terms of types: all MVE
vectors are cast to v16i8.

Reviewers: simon_tatham, MarkMurrayARM, dmgreen, ostannard

Reviewed By: MarkMurrayARM

Subscribers: kristof.beyls, hiraditya, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76299