winch: Introduce winch-environ (#6017)

This commit introduces the `winch-environ` crate. This crate's responsibility is
to provide a shared implementatation of the `winch_codegen::FuncEnv` trait,
which is Winch's function compilation environment, used to resolve module and
runtime specific information needed by the code generation, such as resolving
all the details about a callee in a WebAssembly module, or resolving specific
information from the `VMContext`.

As of this change, the implementation only includes the necessary pieces to
resolve a function callee in a WebAssembly module. The idea is to evolve the
`winch_codegen::FuncEnv` trait as we evolve Winch's code generation.

scripts/publish.rs

@@ -57,6 +57,7 @@ const CRATES_TO_PUBLISH: &[&str] = &[
     "wasmtime-jit",
     "wasmtime-cache",
     "wasmtime-winch",
+    "winch-environ",
     "wasmtime",
     // wasi-common/wiggle
     "wiggle",