Add parsing for labels and guages in statsdreceiver

[sonofachamp]

Description:

Add parsing for gauges and labels.

Link to tracking Issue:
#290

Testing:
Expanded unit test coverage.

Documentation:

[tigrannajaryan]

@sonofachamp is this fixing an open issue?

[sonofachamp]

@tigrannajaryan Not fixing an open issue, but expanding on the StatsD receiver support #290

[asuresh4]

Mostly looks good, left a couple of comments.

Also, please rebase to fix lint.

[codecov]

Codecov Report

Merging #903 into master will increase coverage by 0.04%.
The diff coverage is 96.73%.

@@            Coverage Diff             @@
##           master     #903      +/-   ##
==========================================
+ Coverage   88.47%   88.52%   +0.04%     
==========================================
  Files         245      245              
  Lines       13085    13149      +64     
==========================================
+ Hits        11577    11640      +63     
- Misses       1148     1149       +1     
  Partials      360      360              

Flag	Coverage Δ
#integration	74.88% <ø> (ø)
#unit	87.73% <96.73%> (+0.05%)	⬆️

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

Impacted Files	Coverage Δ
receiver/statsdreceiver/protocol/statsd_parser.go	97.32% <96.73%> (+1.48%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update faaf8d3...0392261. Read the comment docs.

[lubingfeng]

Good to see this is merged. Thanks.
@bogdandrutu @jmacd Just want to check what we need to do and how to test to ensure this statsD receiver is using OTLP compliant protocol.

[lubingfeng]

@jmacd thanks for the input over today's discussion. As suggested, we will consider writing one histogram per point for now.

Questions for aggregation:

1. Every metrics, no matter it's an counter or an timing, to the histogram.
2. What should be collection interval - not customizable, user defined, or receiver specific, given 1 second aggregation interval?

I am more than happy to have a separate call this week to get this sorted out before our implementation.