Switch out from using uvicorn to hypercorn for the pypeline daemon, make
the facilities create hypercorn commands in stand-alone functions, as
they will be re-used for other servers later on.
Make the issuing of notification completely out of band with respect to
the `Pipeline`. Now the `StorageProvider` is responsible for providing
notifications to clients. Since some providers are local-only, there is
a `LOCAL_QUEUE` which allows sensing notifications through a local
queue, re-using the local revng daemon.
Giacomo Vercesi