Feature: #64726 - Added support for multiple FlashMessage queues

See forge#64726


In Extbase ControllerContext the method getFlashMessageQueue() now optionally allows to specify which queue to fetch. If none is specified the default- messagequeue for the current controller/plugin will be used.


In Fluid the flashMessages-ViewHelper also allows to specify a queue to use.

<f:flashMessages queueIdentifier="myQueue" />


Extensions may now render foreign flash message queues and add messages to them.