Open multiple detail dialogs from MultiPullResultDialog at once
This change enables multi-select in the MultiPullResultDialog and
changes the Details button to work with multi-selections. Together with
<https://git.eclipse.org/r/#/c/6291/>, this offers a better workflow for
users who want to review incoming changes from multiple repositories.
The change in PullResultDialog ensures that simple result dialogs
without updates also store their location (but not their size).
Change-Id: If69fc53801db0742bec4bd50302276567fd6b51a
Signed-off-by: Markus Keller <markus_keller@ch.ibm.com>