Implement RFC 11: Redesigning Wasmtime's APIs (#2897)

Implement Wasmtime's new API as designed by RFC 11. This is quite a large commit which has had lots of discussion externally, so for more information it's best to read the RFC thread and the PR thread.

crates/wasi-nn/src/lib.rs

@@ -3,21 +3,4 @@ mod r#impl;
 mod witx;
 
 pub use ctx::WasiNnCtx;
-
-// Defines a `struct WasiNn` with member fields and appropriate APIs for dealing with all the
-// various WASI exports.
-wasmtime_wiggle::wasmtime_integration!({
-    // The wiggle code to integrate with lives here:
-    target: witx,
-    // This must be the same witx document as used above:
-    witx: ["$WASI_ROOT/phases/ephemeral/witx/wasi_ephemeral_nn.witx"],
-    // This must be the same ctx type as used for the target:
-    ctx: WasiNnCtx,
-    // This macro will emit a struct to represent the instance, with this name and docs:
-    modules: {
-        wasi_ephemeral_nn => {
-          name: WasiNn,
-          docs: "An instantiated instance of the wasi-nn exports.",
-        }
-    },
-});
+pub use witx::wasi_ephemeral_nn::add_to_linker;