Render annotation in symbol signature help

[gayanper]

Render parameter annotation on method signature hint. This is useful for null annotation mainly, But also valuable for other type of annotations as well.

[gayanper]

I think we should start with Null annotations if null analysis is enabled, so that we can use the known NullAnnotations by JDT from the preference to decide whether to show or not.

@rgrunber @mickaelistria @jdneo @testforstephen WDYT ?