feat: introduce empty timeline component

ui/app/AppLayouts/Timeline/EmptyTimeline.qml

@@ -0,0 +1,49 @@
+import QtQuick 2.13
+import QtQuick.Controls 2.13
+import QtQuick.Layouts 1.13
+import "../../../imports"
+import "../../../shared"
+import "../../../shared/status"
+
+Rectangle {
+    id: root
+    height: visible ? childrenRect.height : 0
+    width: 375
+    color: "transparent"
+
+    SVGImage {
+        id: sticker
+        anchors.top: parent.top
+        width: 140
+        height: 140
+        source: "../../img/think-sticker.png"
+        anchors.horizontalCenter: parent.horizontalCenter
+    }
+
+    Rectangle {
+        anchors.top: sticker.bottom
+        anchors.topMargin: 0
+        anchors.left: parent.left
+        anchors.leftMargin: 60
+        anchors.right: parent.right
+        anchors.rightMargin: 60
+        border.color: Style.current.border
+        border.width: 1
+        radius: Style.current.padding
+        width: 255
+        height: childrenRect.height + Style.current.padding
+
+        StyledText {
+            horizontalAlignment: Text.AlignHCenter
+            anchors.left: parent.left
+            anchors.leftMargin: Style.current.halfPadding
+            anchors.right: parent.right
+            anchors.rightMargin: Style.current.halfPadding
+            anchors.verticalCenter: parent.verticalCenter
+            text: qsTr("Share what's on your mind and stay updated with your contacts")
+            font.pixelSize: 15
+            color: Style.current.secondaryText
+            wrapMode: Text.WordWrap
+        }
+    }
+}