feat: GRPC health

[amitza]

Description

Closes: #154

Add support for GRPC health checking. This will allow the blackbox exporter to query the GRPC directly.

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Author Checklist

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please add links to any relevant follow up issues.

I have...

• read the contribution guide
• included the correct type prefix in the PR title, you can find examples of the prefixes below:
• confirmed ! in the type prefix if API or client breaking change
• targeted the main branch
• provided a link to the relevant issue or specification
• reviewed "Files changed" and left comments if necessary
• included the necessary unit and integration tests
• updated the relevant documentation or specification, including comments for documenting Go code
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• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

[github-actions]

Test Results

2 173 tests  +3   2 173 ✅ +4   26m 17s ⏱️ +7s
  145 suites ±0       0 💤 ±0 
    7 files   ±0       0 ❌  - 1 

Results for commit 2e16857. ± Comparison against base commit 66aaf13.

♻️ This comment has been updated with latest results.