Add collector example

[psx95]

This PR adds OpenTelemetry Collector based example for metrics export.

Also fixes misconfigured metrics-dashboard json

[codecov]

Codecov Report

Merging #657 (691dea5) into main (cc91e37) will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #657      +/-   ##
==========================================
- Coverage   68.47%   68.39%   -0.09%     
==========================================
  Files          36       36              
  Lines        4559     4559              
==========================================
- Hits         3122     3118       -4     
- Misses       1284     1288       +4     
  Partials      153      153              

see 1 file with indirect coverage changes

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[damemi]

Please also update the gitignore to exclude the new example/metric/collector/metrics binary

[damemi]

Suggested change

	1. Exporting metrics via the SDK.
	2. Exporting metrics via the OpenTelemetry Collector.
	Change the current directory to the example you wish to run - either to `sdk` directory or `collector` directory and then run the example using following commands:
	1. Exporting metrics via the [SDK](sdk).
	2. Exporting metrics via the [OpenTelemetry Collector](collector).
	Change the current directory to the example you wish to run - either to [`sdk`](sdk) directory or [`collector`](collector) directory and then run the example using following commands:

[psx95]

I think the text "SDK" and "OpenTelemetry Collector" in the bullet points should not be a hyperlink to the folders since they are actually intended to explain what component is being used to export metrics.

I will add hyperlinks in the instructions though.

[psx95]

Only the files in example directory are changed. Coverage calculation should not include these files.

[damemi]

only suggestion would be to just drop the debugging exporters, otherwise lgtm