Removed AppsView::getTreeStore method.

Added addAppGroup, addAppGroups, and findAppGroupByName methods to replace functionality in AppsViewPresenter and in the Belphegor repo.
CORE-4088 Copy Workflow now updates Workspace groups.
    
Updated AppsViewPresenter::copyWorkflow to update the app counts in the user's workspace, and to reload the currently selected group if it's the user's Workspace or private apps group.