[RISCV][Clang] Add RVV Type-Convert intrinsic functions.

Fix extension macro condition.

Support below instructions:
1. Single-Width Floating-Point/Integer Type-Convert Instructions
2. Widening Floating-Point/Integer Type-Convert Instructions
3. Narrowing Floating-Point/Integer Type-Convert Instructions

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D99742

GitOrigin-RevId: 01fa222b6d9febc5f5c654ce40137380b6e4c540
8 files changed