PHP 8.2+ Modernization: strict typing, readonly properties, and return types...

PHP 8.2+ Modernization: strict typing, readonly properties, and return types across the entire module. Added type hints to all class properties in MyrestHelper, Normalizers, and REST resources. Applied 'readonly' modifier to all injected services. Added return type hints to all methods in MyrestHelper and 45+ REST resources. Modernized EventSubscribers, OpenAPI generators, and PathProcessors to match PHP 8.2 standards. Also added dependency on myentity in myrest.info.yml.

Closes #3582793