sip: fix "transfer to" label

Change-Id: If3324a34c9be6ff2b09bdab48b148946abe02c51
GitLab: #815

src/app/constant/JamiStrings.qml

@@ -67,6 +67,7 @@ Item {
     property string addToConference: qsTr("Add to conference")
     property string addToConversation: qsTr("Add to conversation")
     property string transferThisCall: qsTr("Transfer this call")
+    property string transferTo: qsTr("Transfer to")
 
     // AccountMigrationDialog
     property string authenticationRequired: qsTr("Authentication required")

src/app/mainview/components/ContactPicker.qml

@@ -100,7 +100,7 @@ Popup {
                 Layout.fillWidth: true
                 Layout.preferredHeight: 35
 
-                placeHolderText: JamiStrings.addParticipant
+                placeHolderText: type === ContactList.TRANSFER ? JamiStrings.transferTo : JamiStrings.addParticipant
 
                 onContactSearchBarTextChanged: {
                     ContactAdapter.setSearchFilter(text)