=htc improve error messages
+htp provide RoutingSettings through RequestContext
!htp consistently prefix simple extraction directives with `extract`
!str #16069 disallows using one Keyed sink/source ambiguously (many times)
Merge pull request #16156 from ktoso/wip-graph-checks-ktoso

!str #16069 disallows using one Keyed sink/source ambiguously (many times)
Merge pull request #16157 from spray/w/RequestContext-withChangedSettings

http: make RoutingSettings a property of the RequestContext
add Future case to javadsl.SinkTest
Merge branch 'fix-type-typos-javadsl-ktoso' into release-2.3-dev
=str removing duplicate fold sink definition on Sink