Add filter for excluding / including metrics by name prefix

[fstab]

Sometimes metrics have issues. Some recent example:

• Performance issues collecting certain JMX metrics, see Add possibility to exclude deadlocks & other Hotspot collectors #672, Adds ability to exclude deadlocked threads from exported metrics #612
• Issues with the exporter-exporter, see Jmx exporter doesn't work with exporter-exporter jmx_exporter#621

With this PR we introduce a "sample name filter" which can be used to include/exclude time series by name, or by name prefix. For example, excluding jvm would exclude all time series starting with jvm.

The "sample name filter" is provided when the exporter is created. The current implementation adds this to two exporters:

• Providing a "sample name filter" for the HTTPServer, via HTTPServer.Builder.
• Providing a "sample name filter" for the exporter Servlet, either programmatically or via Servlet configuration.