[RTL UI] use auto or LTR text direction in some specific cases

Allow TextBoxWidget new text direction/lang parameters to be
set on upper widgets, and propagate them all the way to it
(ScrollTextWidget, InputText, InputDialog, TextViewer).

Use specific non-default ones in some specific cases:
- Force LTR text direction when showing HTML and CSS, and
  configuration files (in some plugins).
- Use Wikipedia server language and text direction when
  showing an article.
- Use auto with Dictionary results, as we don't know the
  dictionary language, and they may contain mixed content.
- Force LTR when showing some paths (still needs more of them)

TextEditor plugin: add 2 new options "Auto paragraph direction"
and "Force paragraph direction LTR".

Footnotes popup: grab HTML direction, and forward it
to MuPDF for proper display.

frontend/apps/reader/modules/readerwikipedia.lua

@@ -488,6 +488,7 @@ function ReaderWikipedia:lookupWikipedia(word, box, get_fullpage, forced_lang)
                 definition = definition,
                 is_fullpage = get_fullpage,
                 lang = lang,
+                rtl_lang = Wikipedia:isWikipediaLanguageRTL(lang),
                 images = page.images,
             }
             table.insert(results, result)