postgres: return unknown records instead of skipping them

[calebdoxsey]

Summary

Instead of skipping unknown records, return them with a struct any of {"id": "ID"}.

Previously when we skipped these records we inadvertently stopped a stream early if too many unknown records were returned, because the stream.pending list would be empty, so the code would think the stream was complete when in fact there were many more records available that would be returned by subsequent SQL calls.

Related issues

Fixes https://github.com/pomerium/internal/issues/1207

Checklist

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

[coveralls]

Coverage: 62.889% (+0.03%) from 62.862% when pulling 4b22880 on cdoxsey/unknown-record-type into 9677e18 on main.

[backport-actions-token]

The backport to 0-20-0 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-0-20-0 0-20-0
# Navigate to the new working tree
cd .worktrees/backport-0-20-0
# Create a new branch
git switch --create backport-3876-to-0-20-0
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 92b50683ff34210a6cb6dff5c0e203f74ae1d5d4
# Push it to GitHub
git push --set-upstream origin backport-3876-to-0-20-0
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-0-20-0

Then, create a pull request where the base branch is 0-20-0 and the compare/head branch is backport-3876-to-0-20-0.