Rollup merge of #98441 - calebzulawski:simd_as, r=oli-obk

Implement simd_as for pointers

Expands `simd_as` (and `simd_cast`) to handle pointer-to-pointer, pointer-to-integer, and integer-to-pointer conversions.

cc ``@programmerjake`` ``@thomcc``

diff --cc compiler/rustc_codegen_llvm/src/intrinsic.rs
Simple merge

diff --cc compiler/rustc_span/src/symbol.rs
Simple merge

diff --cc compiler/rustc_typeck/src/check/intrinsic.rs
Simple merge