feat: Update composer dependencies, add php-cs-fixer, phpstan with config

[ptrcksc]

• Update composer dependencies to php 8.1 max.
• Add php-cs-fixer config.
• Add phpstan config.
• Format code.
• Create phpstan baseline, fix one broken return type.
• Refactor wp.php into seperate classes.
• Add typehints to properties in src/Blocks/
• Format readme into new style.
• Upgrade demo app to laravel 10 (php8.1 support).
• Add image upload example to demo app.
• add eslint config.
• format js code.