Add option to turn off async on building embedded gateway

[virajmehta]

@GabrielBianconi found this pattern that seems to work:

import asyncio
from typing import Union, Awaitable, overload, Literal

import time


class AsyncTensorZeroGateway:
    def __init__(self, *, value: str):
        self.value = value

    @overload
    @staticmethod
    def build(value: str, use_async: Literal[False]) -> "AsyncTensorZeroGateway": ...

    @overload
    @staticmethod
    def build(
        value: str, use_async: Literal[True] = True
    ) -> Awaitable["AsyncTensorZeroGateway"]: ...

    @staticmethod
    def build(
        value: str, use_async: bool = True
    ) -> Union["AsyncTensorZeroGateway", Awaitable["AsyncTensorZeroGateway"]]:
        if use_async:

            async def async_wrapper():
                # Simulate some async work
                c = AsyncTensorZeroGateway(value=value)
                await asyncio.sleep(0.1)
                return c

            return async_wrapper()
        else:
            c = AsyncTensorZeroGateway(value=value)
            time.sleep(0.1)
            return c


class MyOtherClass:
    def __init__(self):
        self.c = AsyncTensorZeroGateway.build(
            value="blocking inside __init__", use_async=False
        )


async def main():
    c0 = AsyncTensorZeroGateway.build(value="blocking", use_async=False)
    c1 = await AsyncTensorZeroGateway.build(value="async", use_async=True)
    c2 = await AsyncTensorZeroGateway.build(value="async without use_async")

    print(c0.value)
    print(c1.value)
    print(c2.value)

    my_other_class = MyOtherClass()
    print(my_other_class.c.value)


asyncio.run(main())

we should add an option for building embedded and http gateway that say async_setup=False (default true)