This change improves optimization of class scanning of `VaadinServletContextInitializer` by reading optional configuration file within a JAR dependency. Configuration file is a regular properties file that can contain `vaadin.allowed-packages` or `vaadin.blocked-packages` to exclude/include packages being scanned by `VaadinServletContextInitializer`. Package exclusion/inclusion effects only classes in the JAR/module where `META-INF/VAADIN/package.properties` is located at.

Notice that this is only affecting the performance of the class scanning of Vaadin specific annotations and types and this feature is not meant to be used for excluding packages from the whole application. E.g. excluding `VaadinServiceInitListener` in a Spring application is not stopping Spring and Vaadin initializing it anyway, although some time-consuming actions like `DevModeServletContextListener` would still exclude it for optimization.

Fixes: #19117