[RTL UI] Bidi-wrap filenames, paths, urls, metadata

bidi.lua:
- Revert "Alias everything to Bidi.nowrap() when in LTR UI,
  as using LTR isolates seems uneeded when already LTR" (part
  of a628714f) which was a wrong assumption: we need proper
  wrappers for all things paths. Enhance some of these wrappers.
- Fix GetText RTL wrapping which was losing empty lines and
  trailing \n.

- Wrap all paths, directories, filenames in the code with
  these wrappers.
- Wrap all book metadata (title, authors...) with BD.auto(),
  as it helps fixing some edge cases (like open/close quotation
  marks which are not considered as bracket types by FriBiDi).
  (Needed some minor logic changes in CoverBrowser.)

- Tweak hyphenation menu text
- Update forgotten SortWidget for UI mirroring
- KoptConfig: update "justification" index for RTL re-ordering,
  following the recent addition of the page_gap_height option.

frontend/apps/reader/modules/readerfont.lua

@@ -1,3 +1,4 @@
+local BD = require("ui/bidi")
 local CenterContainer = require("ui/widget/container/centercontainer")
 local ConfirmBox = require("ui/widget/confirmbox")
 local Device = require("device")
@@ -397,7 +398,7 @@ a { color: black; }
     f:write("</body></html>\n")
     f:close()
     UIManager:show(ConfirmBox:new{
-        text = T(_("Document created as:\n%1\n\nWould you like to read it now?"), fonts_test_path),
+        text = T(_("Document created as:\n%1\n\nWould you like to read it now?"), BD.filepath(fonts_test_path)),
         ok_callback = function()
             UIManager:scheduleIn(1.0, function()
                 self.ui:switchDocument(fonts_test_path)