GDScriptFunctionState, Async implementation.

[darthLeviN]

My suggestion is to expose GDSCriptFunctionState and implement Future for it or it's wrappers.

I wanted to do this but i read that i should make an issue and discuss it first because it's big change.

Is this a useful thing to enable seamless await/async calls in the future?

[TitanNano]

GDSCriptFunctionState exposes a connected signal, so if #261 gets implemented, we can convert the function state into a signal future.

[Bromeon]

Please continue discussion under #261, there are ongoing ideas/efforts.