Remove global state for trap registration (#909)

* Remove global state for trap registration

There's a number of changes brought about in this commit, motivated by a
few things. One motivation was to remove an instance of using
`lazy_static!` in an effort to remove global state and encapsulate it
wherever possible. A second motivation came when investigating a
slowly-compiling wasm module (a bit too slowly) where a good chunk of
time was spent in managing trap registrations.

The specific change made here is that `TrapRegistry` is now stored
inside of a `Compiler` instead of inside a global. Additionally traps
are "bulk registered" for a module rather than one-by-one. This form of
bulk-registration allows optimizing the locks used here, where a lock is
only held for a module at-a-time instead of once-per-function.

With these changes the "unregister" logic has also been tweaked a bit
here and there to continue to work. As a nice side effect the `Compiler`
type now has one fewer field that requires actual mutability and has
been updated for multi-threaded compilation, nudging us closer to a
world where we can support multi-threaded compilation. Yay!

In terms of performance improvements, a local wasm test file that
previously took 3 seconds to compile is now 10% faster to compile,
taking ~2.7 seconds now.

* Perform trap resolution after unwinding

This avoids taking locks in signal handlers which feels a bit iffy...

* Remove `TrapRegistration::dummy()`

Avoid an case where you're trying to lookup trap information from a
dummy module for something that happened in a different module.

* Tweak some comments

crates/api/src/trampoline/func.rs

@@ -287,7 +287,7 @@ pub fn create_handle_with_function(
 
     create_handle(
         module,
-        Some(store),
+        store,
         finished_functions,
         Box::new(trampoline_state),
     )
@@ -322,5 +322,5 @@ pub unsafe fn create_handle_with_raw_function(
         .insert("trampoline".to_string(), Export::Function(func_id));
     finished_functions.push(func);
 
-    create_handle(module, Some(store), finished_functions, state)
+    create_handle(module, store, finished_functions, state)
 }