Create a dedicated picker for java types

It's possible since XWiki 10.10 to specify the type of WikiMacro parameters and since 11.5 to specify the type of WikiMacro content. However those types are only entered in a text input and are never checked until it's already too late (i.e. in the factory of the wikimacro). As a bonus getting suggest on java types would be great.

We should provide a dedicated picker for those java types.