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).

crates/wasi-nn/Cargo.toml

@@ -17,7 +17,7 @@ anyhow = "1.0"
 wiggle = { path = "../wiggle", version = "=0.40.0" }
 
 # These dependencies are necessary for the wasi-nn implementation:
-openvino = { version = "0.3.3", features = ["runtime-linking"] }
+openvino = { version = "0.4.1", features = ["runtime-linking"] }
 thiserror = "1.0"
 
 [build-dependencies]