Fixing Issue #2085

As per #2085

This adds prepopulate parameter, which makes `prepareAssociationsDrawerXMLElement` compatible with both kind (child vs parent) relationship.

It also adds a backward compatibility check since most field are not implementing `prepareAssociationsDrawerXMLElement` and rely on their `prepareTableValue` implementation.

See commit messages for more details.
`@since Symphony 2.4 The prepopulate parameter was added.`, or just add a sentence to the method description :)