[sddm-theme] Apply new username prompt and user list icons

Summary: This patch applies the icons added in D19020 to the Breeze SDDM theme.

Test Plan:
Before

{F6621998}
{F6621997}

After

{F6621999}

{F6622000}

Reviewers: #vdg, #plasma, ngraham, filipf

Reviewed By: #vdg, ngraham, filipf

Subscribers: filipf, plasma-devel

Tags: #plasma

Maniphest Tasks: T10325

Differential Revision: https://phabricator.kde.org/D19129

sddm-theme/Main.qml

@@ -195,7 +195,7 @@ PlasmaCore.ColorScope {
                         visible: !inputPanel.keyboardActive
                     },
                     ActionButton {
-                        iconSource: "system-switch-user"
+                        iconSource: "system-user-prompt"
                         text: i18ndc("plasma_lookandfeel_org.kde.lookandfeel", "For switching to a username and password prompt", "Other...")
                         onClicked: mainStack.push(userPromptComponent)
                         enabled: true
@@ -368,7 +368,7 @@ PlasmaCore.ColorScope {
                         visible: !inputPanel.keyboardActive
                     },
                     ActionButton {
-                        iconSource: "system-switch-user"
+                        iconSource: "system-user-list"
                         text: i18nd("plasma_lookandfeel_org.kde.lookandfeel","List Users")
                         onClicked: mainStack.pop()
                         visible: !inputPanel.keyboardActive