Add Prometheus Server to Ensign

[bbengfort]

Scope of changes

Adds a prometheus server to ensign for o11y.

Also updates the tests to a 1.18 and 1.19 matrix, builds Ensign with Go 1.19 and updates all dependencies.

Fixes SC-9127

Type of change

• new feature
• bug fix
• documentation
• testing
• technical debt
• other (describe)

Acceptance criteria

This is an infrastructure change and will be merged in without review.

Author checklist

• I have manually tested the change and/or added automation in the form of unit tests or integration tests
• I have updated the dependencies list
• I have recompiled and included new protocol buffers to reflect changes I made
• I have added new test fixtures as needed to support added tests
• Check this box if a reviewer can merge this pull request after approval (leave it unchecked if you want to do it yourself)
• I have moved the associated Shortcut story to "Ready for Review"

Reviewer(s) checklist

• Any new user-facing content that has been added for this PR has been QA'ed to ensure correct grammar, spelling, and understandability.

[shortcut-integration]

This pull request has been linked to Shortcut Story #9127: Add Prometheus to Ensign.

[codecov]

Codecov Report

Merging #5 (07b3a9d) into main (92dc4f9) will increase coverage by 4.94%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
+ Coverage   54.29%   59.24%   +4.94%     
==========================================
  Files           9       10       +1     
  Lines         442      530      +88     
==========================================
+ Hits          240      314      +74     
- Misses        182      191       +9     
- Partials       20       25       +5     

Flag	Coverage Δ
unittests	59.24% <ø> (+4.94%)	⬆️

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

Impacted Files	Coverage Δ
...ithub.com/rotationalio/ensign/pkg/config/config.go	41.37% <0.00%> (ø)
...ub.com/rotationalio/ensign/pkg/server/o11y/o11y.go	81.81% <0.00%> (ø)
...c/github.com/rotationalio/ensign/pkg/config/env.go	64.61% <0.00%> (+3.07%)	⬆️

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