This commit adds a new web interceptor that can be configured with a
specific duration. If the response is not produced within this timeline,
the interceptor sends a HTTP error status to the client (by default,
"REQUEST TIMEOUT" but this can be configured) and sends a CANCEL signal
upstream.
This CANCEL signal flows up to controller methods and maually registered
data fetchers, if they have a reactive return type. Processing will be
automatically aborted.
For other types of date fetchers, applications can retrieve a publisher
from the GraphQL context and get notified of cancellations.
Closes gh-450
6d471cd7b8