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

.github/workflows/main.yml

@@ -173,16 +173,6 @@ jobs:
       env:
         CARGO_PROFILE_DEV_DEBUG_ASSERTIONS: false
 
-    # Check whether `crates/wasi-common` cross-compiles to the following targets:
-    # * wasm32-unknown-emscripten
-    # * armv7-unknown-linux-gnueabihf
-    - run: |
-        rustup target add wasm32-unknown-emscripten
-        rustup target add armv7-unknown-linux-gnueabihf
-        sudo apt-get update && sudo apt-get install -y gcc-arm-linux-gnueabihf
-    - run: cargo check --target wasm32-unknown-emscripten -p wasi-common
-    - run: cargo check --target armv7-unknown-linux-gnueabihf -p wasi-common
-
   # Check whether `wasmtime` cross-compiles to aarch64-pc-windows-msvc
   # We don't build nor test it because it lacks trap handling.
   # Tracking issue: https://github.com/bytecodealliance/wasmtime/issues/4992