Menu/ToC: harmonize font sizes (#7795)

Menu: display the right item ("mandatory") with a
smaller font size related to the left item font size,
instead of a function of perpage.
ToC popups: use same font size as in ToC.

frontend/apps/reader/modules/readertoc.lua

@@ -760,6 +760,7 @@ function ReaderToc:onShowToc()
             alignment = "center",
             show_icon = false,
             text = trimmed_text,
+            face = Font:getFace("infofont", self.items_font_size),
         }
         UIManager:show(infomessage)
         return true

frontend/ui/widget/menu.lua

@@ -1110,7 +1110,7 @@ function Menu:updateItems(select_number)
 
     local font_size = self.items_font_size or G_reader_settings:readSetting("items_font_size")
                                      or Menu.getItemFontSize(self.perpage)
-    local infont_size = self.items_mandatory_font_size or Menu.getItemMandatoryFontSize(self.perpage)
+    local infont_size = self.items_mandatory_font_size or (font_size - 4)
     local multilines_show_more_text = self.multilines_show_more_text
     if multilines_show_more_text == nil then
         multilines_show_more_text = G_reader_settings:isTrue("items_multilines_show_more_text")