Support specifying stack slot alignments

#### Feature

See title.

#### Benefit

Correct alignment are necessary to avoid crashes on some architectures and code may depend on correct alignment. In addition rustc checks that the right alignment is used when dereferencing a raw pointer in debug mode. This breaks rayon which allocates a stack value with cacheline alignment and then takes a raw pointer which it later dereferences. See https://github.com/bjorn3/rustc_codegen_cranelift/issues/1381.

#### Implementation

Sort stackslots by alignment for better packing and then add padding as necessary and if the alignment of a stack slot exceeds the ABI stack alignment realign the stack at runtime.

#### Alternatives

Doing dynamic alignment at runtime in the cranelift ir producer. This is slower and has higher stack usage overhead.