Keep some menus open when Tap or Hold (#4189)

TouchMenu: added options to menu items with the following defaults:
    keep_menu_open = false
    hold_keep_menu_open = true
So, default for Tap callback is to close menu, and for Hold callback
to keep menu open.
In both cases, provide the TouchMenu instance as the 1st argument to
the callback functions (instead of a refresh_menu_func I added in #3941)
so the callback can do more things, like closing, refreshing,
changing menu items text and re-ordering...

ReaderZooming: show symbol for default (like it was done for
ReaderFont, ReaderHyphenation...)
TextEditor plugin: update the previously opened files list in real
time, so the menu can be kept open and used as the TextEditor main
interface.
SSH plugin: keep menu open and update the Start/Stop state in real time
ReadTimer plugin: tried to do what feels right (but I don't use it)

Also remove forgotten cp in the move/paste file code

frontend/apps/reader/modules/readerstyletweak.lua

@@ -338,7 +338,6 @@ function ReaderStyleTweak:init()
             self.enabled = not self.enabled
             self:updateCssText(true) -- apply it immediately
         end,
-        hold_may_update_menu = true, -- just to keep menu opened
         hold_callback = function()
             UIManager:show(InfoMessage:new{
                 text = _(
@@ -398,8 +397,7 @@ You can enable individual tweaks on this book with a tap, or view more details a
                     end
                     return title
                 end,
-                hold_may_update_menu = true,
-                hold_callback = function(refresh_menu_func)
+                hold_callback = function(touchmenu_instance)
                     UIManager:show(TweakInfoWidget:new{
                         tweak = item,
                         is_global_default = self.global_tweaks[item.id],
@@ -409,7 +407,7 @@ You can enable individual tweaks on this book with a tap, or view more details a
                             else
                                 self.global_tweaks[item.id] = true
                             end
-                            refresh_menu_func()
+                            touchmenu_instance:updateItems()
                             self:updateCssText(true) -- apply it immediately
                         end
                     })