Persistent session support

[ir4y]

• Add optinal http session parameter to the constructor
• When we do a request

  fhir-py/fhirpy/base/lib.py

  Line 124 in f00a017

  async with aiohttp.ClientSession(headers=headers) as session:

  we should check if session is provided.
  If there is no session, the library creates a new session for this call (current behavior). When session is provided do request should use it instead of creating a new one.
• Implement attach functional and describe best practices for usage AsyncFHIRClient with aiohttp.

class AsyncFHIRClient:
    ...
    @classmethod
    async def attach(
        cls: type["AsyncFHIRClient"], app: aiohttp.web_app.Application
    ) -> AsyncGenerator:
        session = aiohttp.ClientSession()
        client = cls(session=session)
        app[cls.key] = client
        yield
        await session.close()
    ...

app = web.Application()
app.cleanup_ctx.append(AsyncFHIRClient.attach)

• Leverage new approach at https://github.com/Aidbox/aidbox-python-sdk/blob/master/aidbox_python_sdk/main.py#L74

def create_app(sdk: SDK):
    app = web.Application()
    app.cleanup_ctx.append(AidboxClient.attach)
    app.cleanup_ctx.append(init)
    app.update(
        settings=sdk.settings,
        sdk=sdk,
    )
    setup_routes(app)
    return app

[ruscoder]

Related #93