config: validate log levels

[calebdoxsey]

Summary

Validate the log_level and proxy_log_level options to prevent envoy crashing on invalid values.

The supported log levels are the superset of all the know log levels from our documentation, envoy and zerolog, because this option was previously unconstrained, so this should not be a breaking change.

Related issues

• https://github.com/pomerium/internal/issues/1452

Checklist

• reference any related issues
• updated docs
• updated unit tests
• updated UPGRADING.md
• add appropriate tag (improvement / bug / etc)
• ready for review

[coveralls]

coverage: 63.359% (-0.1%) from 63.478% when pulling 09574e0 on cdoxsey/validate-log-levels into a138859 on main.

[kenjenkins]

Nice, I like the idea of introducing an explicit type for the log level.

[backport-actions-token]

The backport to 0-22-0 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-0-22-0 0-22-0
# Navigate to the new working tree
cd .worktrees/backport-0-22-0
# Create a new branch
git switch --create backport-4367-to-0-22-0
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 78e7a3e7d0e8d031995a54f1821daca071a8a685
# Push it to GitHub
git push --set-upstream origin backport-4367-to-0-22-0
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-0-22-0

Then, create a pull request where the base branch is 0-22-0 and the compare/head branch is backport-4367-to-0-22-0.