feat: asgi.entrypoint syntax sugar for nicer asgi apps

[dom96]

This changes a fastapi hello world from:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

import asgi
from workers import WorkerEntrypoint

class Default(WorkerEntrypoint):
    async def fetch(self, request):
        return await asgi.fetch(app, request, self.env)

To:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

import asgi
Default = asgi.entrypoint(app)

Also adds a websockets fastapi test.

[ask-bonk]

LGTM

github run

[hoodmane]

Thanks!