rewrite shared core to allow for concurrency of wasm core

[dschaller]

With the merging of extism/go-sdk#81 it's now possible to have more than one instance of the wasm module. This change modifies the behavior of the shared core to take advantage of this by creating a compiled plugin and spawning off instances of the core when necessary.

It's important to note that this will only help if clients perform the full lifecycle (new client, {action}, release) in parallel as each instance of the wasm module is isolated which means that the credentials cannot be shared across these various instances for different actions.

This change also remains backwards compatible in that if clients only have a single client multiple actions called they will still operate as they currently do in a serial manner, locking to be sure there is only one action accessing the shared wasm core at once.

Testing the resolve function call as the action on a client that resolves 10 references improved performance by ~50% from ~6s to ~3 seconds

[github-actions]

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[dschaller]

from a practical standpoint this is probably unnecessary and I can drop since callWithCtx will always spawn a new instance. Kept it here for some degree of safety for unknown unknowns but if we are ok dropping it would be my preference

[AndyTitu]

@dschaller As discussed with the team, here's a (beta) release that allows you to resolve multiple secret references at once: https://github.com/1Password/onepassword-sdk-go/releases/tag/v0.1.7-beta.1. This feature might address your scalability issues. Let us know how this works for you.