Move filtering and sorting logic to view model

[tobibodamer]

If we want to keep the sorting and filtering the same for each tab:

• subscribe to datagrid.sorted
• Put sortdescriptors in a list
• each time tab is Changed reapply sortdescriptors to new collectionView

If we want to keep different sorting and Filter for each tab:

• add collectionView for Servers to tab Viewmodel
• bind to collectionView