Issue #3611633: Add a metrics generator script and refresh the codebase metrics page

Frank Mablyrequested to merge
issue/yoyaku-3611633:3611633-add-a-metrics into 1.x

Adds scripts/generate-metrics.php (ported from the Orchestra module generator, adapted to Yoyaku) and regenerates docs/metrics.md from it, so the metrics page is no longer hand-maintained. Run from the module root: cloc --exclude-dir=node_modules --by-file --json --quiet . | php scripts/generate-metrics.php

Merge request reports