Fix VP11 negative event numbers while creating new files, when event numbers reach the "int" limit
This MR fixes the negative event numbers observed while creating new files, when the event numbers are large enough to reach the "int" limit.
So, now I moved the event number in {{VP1FilesUtilities}} from {{int}} to {{unsigned long long}}.
That was fixed in several VP1 classes before, and in VP1AlgsEventProd recently (), but that new issue has been found by @lshi, only when enabling the single-event ESD production at P1:
https://atlasop.cern.ch/elisa/display/453544?logbook=ATLAS
This MR fixes that issue and solves ATLASVPONE-569.
NOTE: Hopefully, this MR can be merged into the new release for P1, we need this fix for the onlineEventDisplays single-event ESD production.