Rollup merge of rust-lang#147521 - sayantn:simd-const-intrinsics, r=madsmtm

Make SIMD intrinsics available in `const`-contexts

successor to rust-lang#146568, this PR actually makes the SIMD intrinsics `const`, and modifies the tests to test the const-eval implementations

r? `@tgross35` ig (although feel free to reassign, this is not anything targeted really)

Author: matthiaskrgr