Proxy error reworking

[conradludgate]

Problem

Taking my ideas from #6283 and doing a bit less radical changes. smaller commits.

We currently don't report error classifications in proxy as the current error handling made it hard to do so.

Summary of changes

1. Add a ReportableError trait that all errors will implement. This provides the error classification functionality.
2. Handle Client requests a strongly typed error
   • this error is a ReportableError and is logged appropriately
3. The handle client error only has a few possible error types, to account for the fact that at this point errors should be returned to the user.

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

2418 tests run: 2305 passed, 0 failed, 113 skipped (full report)

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Flaky tests (1)

Postgres 14

• test_pg_regress[4]: release

Code coverage (full report)

• functions: 54.8% (11816 of 21546 functions)
• lines: 82.1% (66050 of 80467 lines)

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_{The comment gets automatically updated with the latest test results
3bbc545 at 2024-02-09T15:38:41.835Z :recycle:}

[khanova]

Looks good! Left a few minor questions.