Reduce contention on the global module rwlock (#4041)

* Reduce contention on the global module rwlock

This commit intendes to close #4025 by reducing contention on the global
rwlock Wasmtime has for module information during instantiation and
dropping a store. Currently registration of a module into this global
map happens during instantiation, but this can be a hot path as
embeddings may want to, in parallel, instantiate modules.

Instead this switches to a strategy of inserting into the global module
map when a `Module` is created and then removing it from the map when
the `Module` is dropped. Registration in a `Store` now preserves the
entire `Module` within the store as opposed to trying to only save it
piecemeal. In reality the only piece that wasn't saved within a store
was the `TypeTables` which was pretty inconsequential for core wasm
modules anyway.

This means that instantiation should now clone a singluar `Arc` into a
`Store` per `Module` (previously it cloned two) with zero managemnt on
the global rwlock as that happened at `Module` creation time.
Additionally dropping a `Store` again involves zero rwlock management
and only a single `Arc` drop per-instantiated module (previously it was
two).

In the process of doing this I also went ahead and removed the
`Module::new_with_name` API. This has been difficult to support
historically with various variations on the internals of `ModuleInner`
because it involves mutating a `Module` after it's been created. My hope
is that this API is pretty rarely used and/or isn't super important, so
it's ok to remove.

Finally this change removes some internal `Arc` layerings that are no
longer necessary, attempting to use either `T` or `&T` where possible
without dealing with the overhead of an `Arc`.

Closes #4025

* Move back to a `BTreeMap` in `ModuleRegistry`

crates/runtime/src/externref.rs

@@ -99,6 +99,7 @@
 //! Examination of Deferred Reference Counting and Cycle Detection* by Quinane:
 //! <https://openresearch-repository.anu.edu.au/bitstream/1885/42030/2/hon-thesis.pdf>
 
+use std::alloc::Layout;
 use std::any::Any;
 use std::cell::UnsafeCell;
 use std::cmp;
@@ -108,7 +109,6 @@ use std::mem;
 use std::ops::Deref;
 use std::ptr::{self, NonNull};
 use std::sync::atomic::{self, AtomicUsize, Ordering};
-use std::{alloc::Layout, sync::Arc};
 use wasmtime_environ::StackMap;
 
 /// An external reference to some opaque data.
@@ -814,7 +814,7 @@ impl VMExternRefActivationsTable {
 /// program counter value.
 pub trait ModuleInfoLookup {
     /// Lookup the module information from a program counter value.
-    fn lookup(&self, pc: usize) -> Option<Arc<dyn ModuleInfo>>;
+    fn lookup(&self, pc: usize) -> Option<&dyn ModuleInfo>;
 }
 
 /// Used by the runtime to query module information.