[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/readerstyletweak.lua

@@ -1,3 +1,4 @@
+local BD = require("ui/bidi")
 local Blitbuffer = require("ffi/blitbuffer")
 local ButtonTable = require("ui/widget/buttontable")
 local CenterContainer = require("ui/widget/container/centercontainer")
@@ -498,7 +499,7 @@ You can enable individual tweaks on this book with a tap, or view more details a
             table.insert(item_table, {
                 title = title,
                 id = file, -- keep ".css" in id, to distinguish between koreader/user tweaks
-                description = T(_("User style tweak at %1"), filepath),
+                description = T(_("User style tweak at %1"), BD.filepath(filepath)),
                 priority = 10, -- give user tweaks a higher priority
                 css_path = filepath,
             })