qml: Add color properties to ContinueButton

This allows components using the ContinueButton to apply their own
color variations.

Author: johnny9

src/qml/controls/ContinueButton.qml

@@ -9,25 +9,38 @@ import org.bitcoincore.qt 1.0
 Button {
     id: root
     hoverEnabled: AppMode.isDesktop
+
+    property color textColor: Theme.color.white
+    property color backgroundColor: Theme.color.orange
+    property color backgroundHoverColor: Theme.color.orangeLight1
+    property color backgroundPressedColor: Theme.color.orangeLight2
+    property color borderColor: "transparent"
+    property color borderHoverColor: "transparent"
+    property color borderPressedColor: "transparent"
+
     contentItem: CoreText {
         text: parent.text
+        color: root.textColor
         bold: true
         font.pixelSize: 18
     }
     background: Rectangle {
         id: bg
         implicitHeight: 46
-        color: Theme.color.orange
+        color: backgroundColor
+        border.color: borderColor
         radius: 5
 
         states: [
             State {
                 name: "PRESSED"; when: root.pressed
-                PropertyChanges { target: bg; color: Theme.color.orangeLight2 }
+                PropertyChanges { target: bg; color: backgroundPressedColor }
+                PropertyChanges { target: bg; border.color: borderPressedColor }
             },
             State {
                 name: "HOVER"; when: root.hovered
-                PropertyChanges { target: bg; color: Theme.color.orangeLight1 }
+                PropertyChanges { target: bg; color: backgroundHoverColor }
+                PropertyChanges { target: bg; border.color: borderHoverColor }
             }
         ]