Add a compile command to Wasmtime.

This commit adds a `compile` command to the Wasmtime CLI.

The command can be used to Ahead-Of-Time (AOT) compile WebAssembly modules.

With the `all-arch` feature enabled, AOT compilation can be performed for
non-native architectures (i.e. cross-compilation).

The `Module::compile` method has been added to perform AOT compilation.

A few of the CLI flags relating to "on by default" Wasm features have been
changed to be "--disable-XYZ" flags.

A simple example of using the `wasmtime compile` command:

```text
$ wasmtime compile input.wasm
$ wasmtime input.cwasm
```

cranelift/Cargo.toml

@@ -53,3 +53,4 @@ wasm = ["wat", "cranelift-wasm"]
 experimental_x64 = ["cranelift-codegen/x64", "cranelift-filetests/experimental_x64", "cranelift-reader/experimental_x64"]
 experimental_arm32 = ["cranelift-codegen/arm32", "cranelift-filetests/experimental_arm32"]
 souper-harvest = ["cranelift-codegen/souper-harvest", "rayon"]
+all-arch = ["cranelift-codegen/all-arch"]