wasi-nn: update openvino crate, use external CI action (#4383)

* ci: replace OpenVINO installer action

To test wasi-nn, we currently use an OpenVINO backend. The Wasmtime CI
must install OpenVINO using a custom GitHub action. This CI action has
not been updated in some time and in the meantime OpenVINO (and the
OpenVINO crates) have released several new versions.
https://github.com/abrown/install-openvino-action is an external action
that we plan to keep up to date with the latest releases. This change
replaces the current CI action with that one.

* wasi-nn: upgrade openvino dependency to v0.4.1

This eliminates a `lazy_static` dependency and changes a few parameters
to pass by reference. Importantly, it enables support for the latest
versions of OpenVINO (v2022.*) in wasi-nn.

* ci: update wasi-nn script to source correct env script

* ci: really use the correct path for the env script

Also, clarify which directory OpenVINO is installed in (the symlink may
not be present).

.github/workflows/main.yml

@@ -310,7 +310,7 @@ jobs:
           submodules: true
       - uses: ./.github/actions/install-rust
       - run: rustup target add wasm32-wasi
-      - uses: ./.github/actions/install-openvino
+      - uses: abrown/install-openvino-action@v3
       - run: ./ci/run-wasi-nn-example.sh
         env:
           RUST_BACKTRACE: 1