WebAssembly: indicate initialization status of runtime

[jzabinski-dolios]

For WebAssembly, the embedder needs to use wasm_exec's run(instance) method in global.Go so that TinyGo's runtime can be initialized prior to calling any of the WebAssembly module's exported functions. But there doesn't seem to be anything in global.Go indicating whether the runtime has been initialized. An easy workaround would be to create a wrapper object for run elsewhere in Javascript, but I feel like it would be useful to store a variable indicating the initialization status of the runtime in global.Go itself.

[dgryski]

This seems pretty doable.

[codefromthecrypt]

do any other compilers do this (rust, clang etc)? might be nice to see how.

[dgryski]

If this ends up being part of #2735 then we could close this one.