CORE-4753, CORE-4752
CORE-4754 Allow editing of group display names in List Trees.

Disabled the onDoubleClick handler in the SelectionItemTreePropertyEditor#TreeGrid to prevent groups from expanding or collapsing when attempting to edit their display fields.
CORE-4758 Fixed NPE in ArgumentSelectionEditor.

Updated the SelectionItemTreePanel#getErrors stub to return an empty list instead of null.(cherry picked from commit ccdba2cb2810e550b232816a41579c6e3ab734a0)
core-4771 core-4772 fix validation in app integration
Merge branch 'master' into STABLE