ApplicationState
When generating the server SDK crate, Pavex examines all the components you registered to determine which singletons will be
used at runtime to process incoming requests.
Pavex then generates a type to group them together, named (unsurprisingly) ApplicationState.
ApplicationState::new
You need to invoke the ApplicationState::new method to build an instance of ApplicationState.
ApplicationState::new takes as input ApplicationConfig and all the types that you marked
as prebuilt.
Inside its body, it'll invoke the constructors for all your singletons in order to build an instance of ApplicationState.