Add NEW_GROUP placeholder type for group models to fix the build

app/src/main/java/com/beemdevelopment/aegis/GroupPlaceholderType.java

@@ -2,12 +2,15 @@ package com.beemdevelopment.aegis;
 
 public enum GroupPlaceholderType {
     ALL,
+    NEW_GROUP,
     NO_GROUP;
 
     public int getStringRes() {
         switch (this) {
             case ALL:
                 return R.string.all;
+            case NEW_GROUP:
+                return R.string.new_group;
             case NO_GROUP:
                 return R.string.no_group;
             default:

app/src/main/java/com/beemdevelopment/aegis/ui/MainActivity.java

@@ -493,7 +493,7 @@ public class MainActivity extends AegisActivity implements EntryListView.Listene
 
         Collection<VaultGroup> groups = _vaultManager.getVault().getUsedGroups();
         List<VaultGroupModel> groupModels = new ArrayList<>();
-        groupModels.add(new VaultGroupModel(getString(R.string.new_group)));
+        groupModels.add(new VaultGroupModel(this, GroupPlaceholderType.NEW_GROUP));
         groupModels.addAll(groups.stream().map(VaultGroupModel::new).collect(Collectors.toList()));
         DropdownHelper.fillDropdown(this, groupsSelection, groupModels);