Initial commit of host metrics network scraper

[james-bebbington]

Link to tracking Issue:
#847

Description:
Added network scraper to the hostmetricsreceiver which uses gopsutil to collect metrics related to network usage & the number of active tcp connections

Exported Metrics:

[codecov-io]

Codecov Report

Merging #930 into master will decrease coverage by 0.00%.
The diff coverage is 86.01%.

@@            Coverage Diff             @@
##           master     #930      +/-   ##
==========================================
- Coverage   85.52%   85.51%   -0.01%     
==========================================
  Files         184      187       +3     
  Lines       13545    13688     +143     
==========================================
+ Hits        11584    11705     +121     
- Misses       1498     1511      +13     
- Partials      463      472       +9     

Impacted Files	Coverage Δ
...eceiver/internal/scraper/networkscraper/factory.go	60.00% <60.00%> (ø)
...internal/scraper/networkscraper/network_scraper.go	81.44% <81.44%> (ø)
receiver/hostmetricsreceiver/factory.go	74.07% <100.00%> (+0.48%)	⬆️
...ternal/scraper/networkscraper/network_constants.go	100.00% <100.00%> (ø)
translator/internaldata/resource_to_oc.go	73.52% <0.00%> (-2.95%)	⬇️

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[bogdandrutu]

Also something bad in the example screenshot the last metric network_tcp_connections should be a gauge not a counter. Problem looks to be somewhere in the translation, looks like you do use gauge, did you change that and took a different snapshot?

[james-bebbington]

Also something bad in the example screenshot the last metric network_tcp_connections should be a gauge not a counter. Problem looks to be somewhere in the translation, looks like you do use gauge, did you change that and took a different snapshot?

Nice spotting. It looks like that's a general bug in the OC prometheus exporter (unrelated to this PR): https://github.com/orijtech/prometheus-go-metrics-exporter/blob/master/prometheus.go#L315 (also L318) - should be derivedPrometheusType instead of prometheus.CounterValue

Track the fix here: orijtech/prometheus-go-metrics-exporter#8