Add HToolTip.instantToggle(), use for some buttons

Used for buttons that trigger a tooltip instantly: if the tooltip is
currently visible, hide it.

src/gui/Base/Buttons/FieldHelpButton.qml

@@ -12,7 +12,7 @@ HButton {
     iconItem.small: true
     toolTip.text: helpText
 
-    onClicked: toolTip.instantShow()
+    onClicked: toolTip.instantToggle()
     onActiveFocusChanged: if (! activeFocus && toolTip.visible) toolTip.hide()
 
     Layout.fillHeight: true

src/gui/Base/HToolTip.qml

@@ -21,6 +21,10 @@ ToolTip {
         instant = false
     }
 
+    function instantToggle(timeout=-1) {
+        visible ? hide() : instantShow(timeout)
+    }
+
 
     delay: instant ? 0 : theme.controls.toolTip.delay
     padding: background.border.width

src/gui/Pages/Chat/RoomHeader.qml

@@ -159,7 +159,7 @@ Rectangle {
                      "unverified devices") :
                 qsTr("All members in this encrypted room are verified")
 
-            onClicked: toolTip.instantShow()
+            onClicked: toolTip.instantToggle()
 
             Layout.preferredWidth: chat.roomInfo.encrypted ? avatar.width : 0
             Layout.fillHeight: true