CORE-3937 CORE-3938 Fix for failed user lookup in DataSharingDialog.

Refactored CollaboratorsUtil::getUserInfo to return a username->Collaborator FastMap to its AsyncCallback.
Refactored LoadPermissionsCallback in DataSharingDialog to display just the username in the SharePanel if that username is not included in the CollaboratorsUtil::getUserInfo response.(cherry picked from commit 571c60fabba692eeee2d62ea7aac61d412b5e0e3)