Add support for collectorNamePattern in config and JavaAgent

[Selikoff]

Per Issue 759, there is no way to prevent certain metrics from being processed, such as jvm_threads_state, as this is run inside CollectionRegistry before the jmx_exporter code can apply any rules. For applications with a lot of threads, this can temporarily cause the application to hang even if the metrics are later filtered out by a rule.

The solution is to add a new pattern value to the config that can be sent into JavaAgent and then passed to the HTTPServer as a SampleNameFilter. This allows metrics to be skipped from processing and resolves issue #759 by adding a config such as:

collectorNamePattern : "^(?!jvm_threads_state$).*$"            
rules:
  - pattern: ".*"

Adding per contributors read me: @fstab @tomwilkie

[fstab]

Awesome, thanks a lot for your PR. I added two minor comments, apart from that it's looking good.

[Selikoff]

@fstab Can we merge this CL? I believe I addressed your concerns.

[dhoard]

@Selikoff looking at the PR... I think the changes should also be made to the standalone HTTP JMX exporter as well.

https://github.com/prometheus/jmx_exporter/blob/main/jmx_prometheus_httpserver_common/src/main/java/io/prometheus/jmx/WebServer.java

[ltning]

I'd also would very much like to see this merged, currently I'm not sure I can deploy this on high-volume systems without risk.

[dhoard]

@Selikoff are you still interested in completing this PR?