[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/readerhighlight.lua

@@ -791,7 +791,7 @@ function ReaderHighlight:viewSelectionHTML(debug_view)
             if css_files then
                 for i=1, #css_files do
                     local button = {
-                        text = T(_("View %1"), css_files[i]),
+                        text = T(_("View %1"), BD.filepath(css_files[i])),
                         callback = function()
                             local css_text = self.ui.document:getDocumentFileContent(css_files[i])
                             local cssviewer