jmx metrics extension: Initial subprocess manager

[rmfitzpatrick]

Description:
Adding a feature - adding a subprocess manager to the jmx metrics extension that will be capable of managing child java processes. This is largely a port of https://github.com/open-telemetry/opentelemetry-collector/blob/master/extension/fluentbitextension/process.go and could potentially be relocated to collector core to satisfy open-telemetry/opentelemetry-collector#1492 in the future.

Link to tracking Issue:

Testing: Integration and unit tests

Documentation: None required, other than changelog that will occur later.

[codecov]

Codecov Report

Merging #1028 into master will increase coverage by 16.07%.
The diff coverage is 96.55%.

@@             Coverage Diff             @@
##           master    #1028       +/-   ##
===========================================
+ Coverage   73.67%   89.74%   +16.07%     
===========================================
  Files          22      275      +253     
  Lines        1018    13510    +12492     
===========================================
+ Hits          750    12125    +11375     
- Misses        217     1016      +799     
- Partials       51      369      +318     

Flag	Coverage Δ
#integration	76.01% <93.10%> (+2.33%)	⬆️
#unit	88.88% <96.55%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...nsion/jmxmetricsextension/subprocess/subprocess.go	96.52% <96.52%> (ø)
...jmxmetricsextension/subprocess/subprocess_linux.go	100.00% <100.00%> (ø)
receiver/kubeletstatsreceiver/kubelet/fs.go	100.00% <0.00%> (ø)
receiver/carbonreceiver/protocol/regex_parser.go	97.22% <0.00%> (ø)
...asticexporter/internal/translator/elastic/utils.go	83.33% <0.00%> (ø)
...sformprocessor/operation_aggregate_label_values.go	100.00% <0.00%> (ø)
...etectionprocessor/internal/aws/ec2/metadata_ec2.go	100.00% <0.00%> (ø)
exporter/signalfxexporter/config.go	90.69% <0.00%> (ø)
receiver/collectdreceiver/receiver.go	71.23% <0.00%> (ø)
receiver/carbonreceiver/receiver.go	95.55% <0.00%> (ø)
... and 258 more

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[rmfitzpatrick]

@bogdandrutu @tigrannajaryan any chance one of you could take a look at this?

[tigrannajaryan]

Adding a feature - adding a subprocess manager to the jmx metrics extension that will be capable of managing child java processes. This is largely a port of https://github.com/open-telemetry/opentelemetry-collector/blob/master/extension/fluentbitextension/process.go and could potentially be relocated to collector core to satisfy open-telemetry/opentelemetry-collector#1492 in the future.

This is now the 3rd instance of a subprocess manager code, right? Perhaps time to actually make it a lib?

[rmfitzpatrick]

@tigrannajaryan this subprocess manager doesn't have robust restart configuration or a persistent stdin mechanism (just writes once). I'd be happy to begin the process of porting this over to collector core but would really appreciate not being blocked on this extension's actual implementation by that work.