Portal Initializer
PortalInitializer is an Initializer that initializes the Portal application context and ActivityProvider.
This initializer performs the following tasks:
Sets the application context in PortalApplicationContextHolder.
Initializes the ActivityProvider with the application instance from the holder.
This class should be used in conjunction with the App Startup library to ensure that the Portal's core components are initialized before other dependent initializers.
Dependencies: This initializer has no dependencies on other initializers.