VSCode: Completion for annonymous inner classes improved.

[dbalek]

Code completion for anonymous inner class constructor should generate default implementation for all abstract methods.
E.g. code completion for:

Runnable r = new Runnable|

should generate:

Runnable r = new Runnable() {
    @Override
    public void run() {
        throw new UnsupportedOperationException("Not supported yet.");
    }
}