As we have incoming changes in Gerrit which wants to use Java 11
featureas and most of the platform plug-ins have moved to Java 11, I
think we should also update JFace.

Includes a fix in SubContrributionManager which became visible after the
Java version change.

Change-Id: I25ebf3e8004fa7d2caac1d56e247d5c997981344
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.ui/+/181970
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>