Allow configuration of wasmtime features

Currently, `containerd-shim-wasmtime-v1` doesn't seem to be able to configure the underlying wasmtime runtime.

https://github.com/containerd/runwasi/blob/7a9c892274a9b4353f7bbd5a0e4132ab51f0624d/crates/containerd-shim-wasmtime/src/instance.rs#L67-L82

This limitation prevent us from running our Wasm OCI artifact, built from component binary that requires `-W function-references,gc` unable to run on the shim. (on k8s, it ends up with `CrashLoopBackOff`).

https://github.com/users/tanishiking/packages/container/package/scala-wasm-echo-server (Wasm OCI artifact built by `wkg oci push` from Wasm component binary that implements `wasi:http/proxy`)

https://github.com/scala-wasm/scala-wasm/tree/scala-wasm/examples/echo-server

Is there a way to configure wasmtime from `runwasi`?

Start in crates/containerd-shim-wasmtime/src/instance.rs at lines 67-82 to trace how the underlying Wasmtime runtime is created. Reproduce the failure with the linked scala-wasm-echo-server component, then determine how runtime features such as function-references and gc could be configured and verify that the Wasm OCI artifact runs successfully.

Written by the indexing model from the issue text.