Rate limiter support in ooniservices

[hellais]

Implements: #910

[aagbsn]

It looks like the tests hey it looks like tests/run fail with this error:

(.hatchenv) 179d1346c7d2:/project/ooni/backend/ooniapi/services/oonimeasurements$ make run
hatch run uvicorn oonimeasurements.main:app
INFO:     Started server process [5211]
INFO:     Waiting for application startup.
ERROR:    Traceback (most recent call last):
  File "/project/ooni/backend/ooniapi/services/oonimeasurements/.venv/lib/python3.12/site-packages/starlette/routing.py", line 705, in lifespan
    async with self.lifespan_context(app) as maybe_state:
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/contextlib.py", line 210, in __aenter__
    return await anext(self.gen)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/project/ooni/backend/ooniapi/services/oonimeasurements/src/oonimeasurements/main.py", line 34, in lifespan
    app.add_middleware(RateLimiterMiddleware, redis_url=settings.redis_url)
  File "/project/ooni/backend/ooniapi/services/oonimeasurements/.venv/lib/python3.12/site-packages/starlette/applications.py", line 129, in add_middleware
    raise RuntimeError("Cannot add middleware after an application has started")
RuntimeError: Cannot add middleware after an application has started