feat: Support wasmedge plugins

[CaptainVincent]

It's a feature PR

By the way, please note that this feature currently only functions when dynamically linking the WasmEdge library to the WasmEdge shim.

For building this, you can use the following command:
cargo build --package containerd-shim-wasmedge --no-default-features

In addition, I have provided all the WasmEdge runtime demo cases via containerd (here), including the wasinn plugin demo related to this feature. Considering that these demos may only be supported with the WasmEdge shim, I plan to relocate and maintain them under the WasmEdge or Second State Org's repository. At the same time, I will ensure that they run demos daily in CI and guarantee that these demos are always executed based on the latest upstream code.

[Mossaka]

Thanks! Added a few comments.

[jprendes]

Where are the plugins supposed to be found?
In the host? Or in the container image?

If inside the container image, I don't see why we need to fiddle with the mount points, as libcontainer will have already handled that for us.
If it's in the host, by this point it's too late and the process doesn't have access to any path ouside the container root.

[CaptainVincent]

Where are the plugins supposed to be found? In the host? Or in the container image?

If inside the container image, I don't see why we need to fiddle with the mount points, as libcontainer will have already handled that for us. If it's in the host, by this point it's too late and the process doesn't have access to any path ouside the container root.

The plugin is a .so file loaded through dlopen, and it is not specifically restricted to running within either the host or the container. As mentioned earlier, this mount aspect belongs to legacy code to handle filesystem for wasm, and I will remove it and modify the way my example is used.

[CaptainVincent]

The statically linked version is also about to support plugin functionality, but the changes made only depend on the Wasmedge library. Therefore, after merging this PR, upstream will only need to await the release of the new SDK version to enable it in both ways.

[jprendes]

LGTM!

[jsturtevant]

LGTM

[devigned]

lgtm! Thank you, @CaptainVincent.