OpenTelemetry metrics collector implementation

[rjbaucells]

Proposed Changes

This PR adds a MetricsCollector implementation using OpenTelemetry.

Types of Changes

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• Bugfix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (correction or otherwise)
• Cosmetics (whitespace, appearance)

Checklist

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the PR. If you're unsure about any of them, don't hesitate to ask on the
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• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

[michaelklishin]

Thank you for contributing!

[acogoluegnes]

Thanks!