Query command for database queries and more

This week in Rails covers several new features and fixes merged into the Rails codebase. The headline addition is a new `rails query` command that runs read-only database queries and returns structured JSON output, with subcommands like `query schema`, `query models`, and `query explain`. Other changes include appending `charset=utf-8` to Content-Type headers for static CSS and HTML files, adding an offline fallback page to the PWA scaffold, a rewrite of the Layouts and Rendering guide, a fix for IO copy stream writing to Action Controller Live Buffer, a fix for `reset_counters` with string IDs, a performance improvement in `ParameterFilter` using hash lookups for exact-match regexp filters, and stronger documentation warnings about Active Storage redirect and proxy mode security risks.