add support for @Named annotation

[martinlippert]

We should support the @Named annotation with:

• specific bean symbol (similar to @Component)
• register bean definition in the bean index (including injection points, again similar to @Component)

[martinlippert]

This should also include:

• auto completion for the value of the annotation (bean names as well as otherwise mentioned values of the same annotation, similar to the @Qualifier annotation)
• go to definition (if a bean name is referenced)
• find references (all occurrences of the the value)