4850 bring leaving space experience in line with web (#6062)

* Bring leaving space experience in line with Web #4850

- Done

RiotSwiftUI/Modules/Spaces/MatrixItemChooser/Service/MatrixSDK/MatrixItemChooserService.swift

@@ -61,6 +61,13 @@ class MatrixItemChooserService: MatrixItemChooserServiceProtocol {
     var loadingText: String? {
         itemsProcessor.loadingText
     }
+    var itemCount: Int {
+        var itemCount = 0
+        for section in sections {
+            itemCount += section.items.count
+        }
+        return itemCount
+    }
 
     // MARK: - Setup
     
@@ -118,6 +125,22 @@ class MatrixItemChooserService: MatrixItemChooserServiceProtocol {
             }
         }
     }
+    
+    func selectAllItems() {
+        var newSelection: Set<String> = Set()
+        for section in sections {
+            for item in section.items {
+                newSelection.insert(item.id)
+            }
+        }
+        self.selectedItemIds = newSelection
+        selectedItemIdsSubject.send(selectedItemIds)
+    }
+    
+    func deselectAllItems() {
+        self.selectedItemIds = Set()
+        selectedItemIdsSubject.send(selectedItemIds)
+    }
 
     // MARK: - Private