+str #15193 Expose some test producers in StreamTestKit
=tes #15165 MetricsKit should not nullpointer on racy graphite usage
The report() call can come from multiple threads in our code,
yet it was opening/closing a shared graphite client instance in this
method, causing NPE when periodic reporting kicked in during a manual
report() call. We want to be able to do this - thus rewrite to safe impl

Removed metrics-graphite dependency, replaced by in house impl.
The previous was using discrete write() calls, which could be entangled
when called from multiple threads, and produce invalid metric lines.
Current impl is simpler and threadsafe, as the lock for write(String) to
aquired for the entire string lenght's write (unlike multiple write calls).

Resolves #15165

Conflicts:
	akka-testkit/src/test/scala/akka/testkit/metrics/reporter/AkkaGraphiteReporter.scala
	project/Dependencies.scala
Merge pull request #15210 from akka/wip-15193-test-producers-patrikwn

+str #15193 Expose some test producers in StreamTestKit
+str #15195 Add internal SynchronousProducerFromIterable
+str #15197 Add flow.append(duct)

* and duct.append(duct), and missing javadsl flow.produceTo
Merge pull request #15202 from akka/wip-15195-producer-interable-patriknw

+str #15195 Add internal SynchronousProducerFromIterable
Merge pull request #15204 from akka/wip-15197-flow-append-duct-patriknw

+str #15197 Add flow.append(duct)
+str #15173 Add user support for actor consumer endpoint

* with full control over back pressure
* and pluggable request strategy
Merge pull request #15214 from akka/wip-15173-actor-consumer-patriknw

+str #15173 Add user support for actor consumer endpoint
=proj updating jmh plugin version to 0.1.2
Merge pull request #15261 from ktoso/update-jmh-plugin

=proj update jmh plugin to 0.1.2
+scr additional functions for tagging issues on github
Merge pull request #15263 from ktoso/scr-github-tagging-pr-validator

+scr functions for tagging issues on github, for pr-validator
Merge pull request #15247 from ktoso/port-graphite-client-rewrite-metricskit-ktoso

=tes #15228 backport - metricskit fix for racy graphite client (for validation)
=act #15165 should fix out-of-bounds in actor creation
Other than that, also improved failure logging when AIOOB happens in the histogram
Added a test which shows why the updateWithExpectedInterval method
should be preferred too.

Backport from master

Conflicts:
	akka-testkit/src/test/scala/akka/testkit/metrics/reporter/AkkaGraphiteReporter.scala
=src jenkins needs explicit bash usage
Merge pull request #15266 from ktoso/jenkins-needs-bash-shebang

=scr jenkins needs to use bash, not sh
Merge pull request #15264 from ktoso/port-metrics-kit-fixes-from-master

=tes,act forward port of metricskit / test stability improvements
+tes added AkkaMetricsKit to ease use with AkkaSpec
+ Improved printing when running from a spec (use info stead of
println), so the results appear after the test name, not before it like
it happens with unbuffered println()
=per #15064 persistence perf spec is now MetricsKit aware