Add missing common comment for getter/setter

[limingchina]

Currently, the common comments defined in the lime file for getter/setter are thrown away in the generated comment.

For example

    // Some very useful property.
    // @get Gets some very useful property.
    // @set Sets some very useful property.
    property SomeProperty: Usefulness

as seen in the test: https://github.com/heremaps/gluecodium/blob/cddc88a1ea67f905cca56833a59e37b7524a0baf/gluecodium/src/test/resources/smoke/comments/input/CommentsInterface.lime#L68

The current output for dart is

  /// Gets some very useful property.
  bool get isSomeProperty;
  /// Sets some very useful property.
  set isSomeProperty(bool value);

as in https://github.com/heremaps/gluecodium/blob/cddc88a1ea67f905cca56833a59e37b7524a0baf/gluecodium/src/test/resources/smoke/comments/output/dart/lib/src/smoke/comments_interface.dart#L80

The expected output is add the common part "Some very useful property." to the docs for both the getter and setter. Maybe append to the specific comments for getter and setter as a separate section for detailed explanation?

[limingchina]

It seems that one can't handle this gracefuly because Swift doesn't have separate getter and setter. For now, we have duplicate the doc.