New stations assigning and printing logic

[aasalobrena]

First part of #131.

• printStationsForBlankScorecards replaces printStations in groupifier.CompetitionConfig. It determines whether station boxes needs to be printed in blank, OTS, and custom scorecards.
• Assigned rounds scorecards print the station number based entirely on the assignment.
• Station number assignment is now round-dependent and is stored in assignStations in the groupifier.ActivityConfig extension, following the same pattern as the assignJudges property.
• Non-assigned rounds scorecards print the station number based on the assignStations property, with printStationsForBlankScorecards as a fallback when another grouping tool is used.