misc: use BackButton when necessary

Change-Id: I220038edeb4dc83d85d8e4048168c97c2a992940

src/constant/JamiStrings.qml

@@ -430,6 +430,7 @@ Item {
 
     // PluginListSettingsView
     property string addNewPlugin: qsTr("Add new plugin")
+    property string goBackToPluginsList: qsTr("Go back to plugins list")
 
     // PreferenceItemDelegate
     property string selectFile: qsTr("Select a file")

src/mainview/components/PluginHandlerPicker.qml

@@ -201,15 +201,14 @@ Popup {
                 RowLayout {
                     height: JamiTheme.preferredFieldHeight
 
-                    PushButton {
+                    BackButton {
                         id: backButton
+
                         Layout.leftMargin: 5
                         Layout.topMargin: 5
 
-                        imageColor: JamiTheme.textColor
-                        source: JamiResources.ic_arrow_back_24dp_svg
-                        toolTipText: qsTr("Go back to plugins list")
-                        hoverEnabled: true
+                        toolTipText: JamiStrings.goBackToPluginsList
+
                         onClicked: {
                             stack.pop(null, StackView.Immediate)
                         }

src/settingsview/components/SettingsHeader.qml

@@ -33,19 +33,12 @@ RowLayout {
     property string title: ""
     signal backArrowClicked
 
-    PushButton {
+    BackButton {
         id: backToSettingsMenuButton
 
         Layout.preferredWidth: JamiTheme.preferredFieldHeight
         Layout.preferredHeight: JamiTheme.preferredFieldHeight
 
-        radius: JamiTheme.preferredFieldHeight
-        source: JamiResources.ic_arrow_back_24dp_svg
-        normalColor: JamiTheme.backgroundColor
-        imageColor: JamiTheme.textColor
-        toolTipText: JamiStrings.back
-        hoverEnabled: true
-
         visible: mainView.sidePanelOnly
 
         onClicked: backArrowClicked()