Update and standardise Hungarian translation

[smileyhead]

I am opening this PR to update the Hungarian translation, as well as to update the language structure as per upstream changes in DokuWiki (dokuwiki/dokuwiki#4509).

My changes are based on the standards and guidelines set by the Hungarian Free Software Foundation – any terminology changes are based on their dictionary as well.

The summary of my changes is as follows:

• Updated Hungarian translation ('hu')
• Renamed 'hu' to 'hu-informal' and created a new (formal) 'hu' translation. (Hungarian software generally defaults to formal.)
• Fixed quotation mark usage: "" → „”
• Removed some oddities, such as the plugin referring to itself in first person (‘Should I do XY?’ → ‘Should XY be done?’).
• Fixed terminology usage:
  • plugin: csatoló → bővítmény
  • emphasis: hangsúly → kiemelés
  • toolbar: eszközsor → eszköztár

Note: Since this translation does not currently address the user directly, 'hu' and 'hu-informal' are the same.