Remove need for polkit, launch any ArchUpdater update through terminal

ArchUpdater: rely on `TERMINAL` environment variable
README: Add explanation for the `TERMINAL` environment variable

Widgets/NTextInput.qml

@@ -12,8 +12,6 @@ ColumnLayout {
   property bool readOnly: false
   property bool enabled: true
   property int inputMaxWidth: 420 * scaling
-  property color labelColor: Color.mOnSurface
-  property color descriptionColor: Color.mOnSurfaceVariant
 
   property alias text: input.text
   property alias placeholderText: input.placeholderText
@@ -27,8 +25,6 @@ ColumnLayout {
   NLabel {
     label: root.label
     description: root.description
-    labelColor: root.labelColor
-    descriptionColor: root.descriptionColor
     visible: root.label !== "" || root.description !== ""
   }