[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/cloudstorage/cloudstorage.lua

@@ -1,3 +1,4 @@
+local BD = require("ui/bidi")
 local ButtonDialog = require("ui/widget/buttondialog")
 local ButtonDialogTitle = require("ui/widget/buttondialogtitle")
 local ConfirmBox = require("ui/widget/confirmbox")
@@ -343,7 +344,7 @@ end
 
 function CloudStorage:onMenuHold(item)
     if item.type == "folder_long_press" then
-        local title = T(_("Select this directory?\n\n%1"), item.url)
+        local title = T(_("Select this directory?\n\n%1"), BD.dirpath(item.url))
         local onConfirm = self.onConfirm
         local button_dialog
         button_dialog = ButtonDialogTitle:new{
@@ -524,7 +525,7 @@ function CloudStorage:synchronizeSettings(item)
     local dropbox_sync_folder = item.sync_source_folder or "not set"
     local local_sync_folder = item.sync_dest_folder or "not set"
     syn_dialog = ButtonDialogTitle:new {
-        title = T(_("Dropbox folder:\n%1\nLocal folder:\n%2"), dropbox_sync_folder, local_sync_folder),
+        title = T(_("Dropbox folder:\n%1\nLocal folder:\n%2"), BD.dirpath(dropbox_sync_folder), BD.dirpath(local_sync_folder)),
         title_align = "center",
         buttons = {
             {