Refactor Composer

- Have a simple HTextArea component instead of HScrollTextArea
- Split composer parts between multiple files

src/gui/Pages/Chat/Composer/Composer.qml

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+import QtQuick 2.12
+import QtQuick.Controls 2.12
+import QtQuick.Layouts 1.12
+import "../../../Base"
+
+Rectangle {
+    property alias eventList: messageArea.eventList
+
+
+    function takeFocus() { messageArea.forceActiveFocus() }
+
+
+    implicitHeight:
+        Math.max(theme.baseElementsHeight, messageArea.implicitHeight)
+
+    color: theme.chat.composer.background
+
+
+    HRowLayout {
+        anchors.fill: parent
+
+        HUserAvatar {
+            id: avatar
+            radius: 0
+            userId: messageArea.writingUserId
+
+            mxc:
+                messageArea.writingUserInfo ?
+                messageArea.writingUserInfo.avatar_url :
+                ""
+
+            displayName:
+                messageArea.writingUserInfo ?
+                messageArea.writingUserInfo.display_name :
+                ""
+        }
+
+        ScrollView {
+            Layout.fillHeight: true
+            Layout.fillWidth: true
+
+            MessageArea { id: messageArea}
+        }
+
+        UploadButton {
+            Layout.fillHeight: true
+        }
+    }
+}