Rollup merge of #108022 - CraftSpider:align-bytes, r=oli-obk

Support allocations with non-Box<[u8]> bytes

This is prep work for allowing miri to support passing pointers to C code, which will require `Allocation`s to be correctly aligned. Currently, it just makes `Allocation` generic and plumbs the necessary changes through the right places.

The follow-up to this will be adding a type in the miri interpreter which correctly aligns the bytes, using that for the Miri engine, then allowing Miri to pass pointers into these allocations to C calls.

Based off of #100467, credit to ```@emarteca``` for the code

Author: matthiaskrgr

src/machine.rs

@@ -777,10 +777,11 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
 
     type Provenance = Provenance;
     type ProvenanceExtra = ProvenanceExtra;
+    type Bytes = Box<[u8]>;
 
     type MemoryMap = MonoHashMap<
         AllocId,
-        (MemoryKind<MiriMemoryKind>, Allocation<Provenance, Self::AllocExtra>),
+        (MemoryKind<MiriMemoryKind>, Allocation<Provenance, Self::AllocExtra, Self::Bytes>),
     >;
 
     const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);