Update workflows; Add dependabot and codeql; Optimize workflows

[thelovekesh]

Summary

• Introduced caching and optimized workflows to use composure actions for repetitive tasks.
• Switch to bash-based WP tests setup for maximum backward compatibility.
• Add dependabot config to update deps, using "groups" per month.
• Add codeql config for scanning JS files for any vulnerabilities.
• Consolidate standalone linting and testing workflows in single files.
• Remove dependency from third-party workflows for canceling concurrent workflows.
• Update workflows to the latest version.
• Restrict permissions in the workflows for the sake of runner security.

Relevant technical choices

Checklist

• PR has either [Focus] or Infrastructure label.
• PR has a [Type] label.
• PR has a milestone or the no milestone label.