Add option to select other positions that you want to apply for

[dakaza98]

When some people apply for a position within a committee or work-group, they apply for multiple positions. At the moment you can only apply to one position at a time. Instead there should be an option on the page where you apply to a position to select other positions that you want to apply for as well. It should also be possible to only apply for the position you are viewing.

When a user selects other positions and applies/saves draft, a new application should be created for all the selected positions. All the parts of the application will be the same across all the applications that are created.

The positions that a user can choose from should only be positions within the same committee or work-group as the position they are viewing and are open for applications. This is because if you apply for two positions in different committees or work-groups, it is most likely that you want to write different things in the the application.