Use GitHub actions

[Zodiac1978]

Add some Continuous Integration CI/CD workflow:

• GitHub action for deployment to wordpress.org
• GitHub action for static analysis (e.g. PHPStan)
• GitHub action for searching for typos
• GitHub action for checking for WordPress coding standards (WPCS)
• GitHub actions for Plugin Check

[apermo]

Which exact WPCS ruleset are you aiming for? I'm happy to provide the PR for that. Do you intend any customizations, modernizations or hardening?