Auto merge of #53671 - RalfJung:miri-refactor, r=oli-obk
Miri engine cleanup
* Unify the two maps in memory to store the allocation and its kind together.
* Share the handling of statics between CTFE and miri: The miri engine always
uses "lazy" `AllocType::Static` when encountering a static. Acessing that
static invokes CTFE (no matter the machine). The machine only has any
influence when writing to a static, which CTFE outright rejects (but miri
makes a copy-on-write).
* Add an `AllocId` to by-ref consts so miri can use them as operands without
making copies.
* Move responsibilities around for the `eval_fn_call` machine hook: The hook
just has to find the MIR (or entirely take care of everything); pushing the
new stack frame is taken care of by the miri engine.
* Expose the intrinsics and lang items implemented by CTFE so miri does not
have to reimplement them.
* Allow Machine to hook into foreign statics (used by miri to get rid of some other hacks).
* Clean up function calling.
* Switch const sanity check to work on operands, not mplaces.
* Move const_eval out of rustc_mir::interpret, to make sure that it does not access private implementation details.
In particular, we can finally make `eval_operand` take `&self`. :-)
Should be merged after https://github.com/rust-lang/rust/pull/53609, across which I will rebase.