wiggle: make wasmtime a mandatory dep, get rid of own Trap enum (#5137)

* wiggle: no longer need to guard wasmtime integration behind a feature

this existed so we could use wiggle in lucet, but lucet is long EOL

* replace wiggle::Trap with wiggle::wasmtime_crate::Trap

* wiggle tests: unwrap traps because we cant assert_eq on them

* wasi-common: emit a wasmtime::Trap instead of a wiggle::Trap

formally add a dependency on wasmtime here to make it obvious, though
we do now have a transitive one via wiggle no matter what (and therefore
can get rid of the default-features=false on the wiggle dep)

* wasi-nn: use wasmtime::Trap instead of wiggle::Trap

there's no way the implementation of this func is actually
a good idea, it will panic the host process on any error,
but I'll ask @mtr to fix that

* wiggle test-helpers examples: fixes

* wasi-common cant cross compile to wasm32-unknown-emscripten anymore

this was originally for the WASI polyfill for web targets. Those days
are way behind us now.

* wasmtime wont compile for armv7-unknown-linux-gnueabihf either

crates/wiggle/tests/strings.rs

@@ -86,8 +86,9 @@ impl HelloStringExercise {
             self.string_ptr_loc.ptr as i32,
             self.test_word.len() as i32,
             self.return_ptr_loc.ptr as i32,
-        );
-        assert_eq!(res, Ok(types::Errno::Ok as i32), "hello string errno");
+        )
+        .unwrap();
+        assert_eq!(res, types::Errno::Ok as i32, "hello string errno");
 
         let given = host_memory
             .ptr::<u32>(self.return_ptr_loc.ptr)
@@ -207,8 +208,9 @@ impl MultiStringExercise {
             self.sc_ptr_loc.ptr as i32,
             self.c.len() as i32,
             self.return_ptr_loc.ptr as i32,
-        );
-        assert_eq!(res, Ok(types::Errno::Ok as i32), "multi string errno");
+        )
+        .unwrap();
+        assert_eq!(res, types::Errno::Ok as i32, "multi string errno");
 
         let given = host_memory
             .ptr::<u32>(self.return_ptr_loc.ptr)
@@ -285,8 +287,9 @@ impl OverlappingStringExercise {
             (self.sa_ptr_loc.ptr + self.offset_c) as i32,
             a_len - self.offset_c as i32,
             self.return_ptr_loc.ptr as i32,
-        );
-        assert_eq!(res, Ok(types::Errno::Ok as i32), "multi string errno");
+        )
+        .unwrap();
+        assert_eq!(res, types::Errno::Ok as i32, "multi string errno");
 
         let given = host_memory
             .ptr::<u32>(self.return_ptr_loc.ptr)