Show toast message if backup was created successfully

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

@@ -438,6 +438,7 @@ public class PreferencesFragment extends PreferenceFragmentCompat {
             if (_prefs.isBackupsEnabled()) {
                 try {
                     _vault.backup();
+                    Toast.makeText(getActivity(), R.string.backup_successful, Toast.LENGTH_LONG).show();
                 } catch (VaultManagerException e) {
                     e.printStackTrace();
                     Dialogs.showErrorDialog(getContext(), R.string.backup_error, e);

app/src/main/res/values/strings.xml

@@ -158,6 +158,7 @@
     <string name="disable_encryption_description">Are you sure you want to disable encryption? This will cause the vault to be stored in plain text.</string>
     <string name="enable_encryption_error">An error occurred while enabling encryption</string>
     <string name="disable_encryption_error">An error occurred while disabling encryption</string>
+    <string name="backup_successful">The backup was created successfully</string>
     <string name="backup_error">An error occurred while trying to create a backup</string>
     <string name="permission_denied">Permission denied</string>
     <string name="andotp_new_format">New format (v0.6.3 or newer) </string>