[Clang] Enable warnings on lax vector conversions

[mikolaj-pirog]

This makes clang emit warnings on code that does implicit vector conversions, like so:

__m512 a;
__m512d b;

a = b;

For more, see https://discourse.llvm.org/t/rfc-making-flax-vector-conversions-none-the-default/88008

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.