[sui adapter] expose entrypoint for calling public function with return values

[sblackshear]

This is a blocker for #3815.

adapter::execute_function isn't quite suitable for this because it can only invoke entry functions, and it only allows primitive return values. We will need a different code path that can

• call public functions that take any argument type (pure values, immutable/mutable refs, etc)
• return any non-reference type(s)
• extract the return values and pipe them into a REST response for the API above

[0xys]

I like this feature!

Do you have an estimate of the time of delivery?

[ernest-zulpukarov]

wen