add_contact: change default message when adding someone

Currently when adding a new user there is no indication
in the chatview whether that person is in your contacts.
This patch aims to work towards a chatview which makes
this interaction clearer.

Change-Id: I68827f42b0e97e0ee80e631ce057016eb8df0305

src/app/mainview/components/MessageBar.qml

@@ -110,7 +110,7 @@ Rectangle {
                 id: messageBarTextArea
                 objectName: "messageBarTextArea"
 
-                placeholderText: JamiStrings.writeTo.arg(CurrentConversation.title)
+                placeholderText: CurrentConversation.isTemporary ? JamiStrings.writeToNewContact.arg(CurrentConversation.title) : JamiStrings.writeTo.arg(CurrentConversation.title)
 
                 anchors {
                     right: (showTypo) ? previewButton.left : messageRow.right

src/app/net/jami/Constants/JamiStrings.qml

@@ -779,6 +779,7 @@ Item {
     property string inReplyToMe: qsTr("Me")
     property string reply: qsTr("Reply")
     property string writeTo: qsTr("Write to %1")
+    property string writeToNewContact: qsTr("Send a message to %1 in order to add them as a contact")
     property string edit: qsTr("Edit")
     property string edited: qsTr("Edited")
     property string joinCall: qsTr("Join call")