sddm-theme: fix missing password field on "Other" page

On this page there is no concept of the user being passwordless because
no username has been specified by the user yet; we cannot know ahead of
time. As a result, userList.currentItem.needsPassword is blank so the
password field gets hidden.

We should just assume that in username/password entry mode, all users
have a password set. For any users where this is not the case, they can
just leave the password blank, and it's not any worse than it was in
Plasma 5.22.

BUG: 443737
FIXED-IN: 5.23.1

sddm-theme/Login.qml

@@ -83,7 +83,7 @@ SessionManagementScreen {
                 }
             }
 
-            visible: userList.currentItem.needsPassword
+            visible: root.showUsernamePrompt || userList.currentItem.needsPassword
 
             Keys.onEscapePressed: {
                 mainStack.currentItem.forceActiveFocus();
@@ -119,7 +119,7 @@ SessionManagementScreen {
 
             icon.name: text.length == 0 ? "go-next" : ""
 
-            text: userList.currentItem.needsPassword ? "" : i18n("Log In")
+            text: root.showUsernamePrompt || userList.currentItem.needsPassword ? "" : i18n("Log In")
             onClicked: startLogin();
         }
     }