Some little changes to "ar" locale

Overwrite values from rails-i18n by manually overwriting in every locale.
We want numbers like 1.5K in every language

* Redesign /terms page

* Fix tests

* Remove unused keys

* Redesign extended information page

* Remove unused keys

* Add $ui-base-lighter-color variable to SCSS

* Redesign the landing page, mount public timeline on it

* Adjust the standalone mounted component to the lacking of router

* Adjust auth layout pages to new design

* Fix tests

* Standalone public timeline polling every 5 seconds

* Remove now obsolete translations

* Add responsive design for new landing page

* Address reviews

* Add floating clouds behind frontpage form

* Use access token from public page when available

* Fix mentions and hashtags links, cursor on status content in standalone mode

* Add footer link to source code

* Fix errors on pages that don't embed the component, use classnames

* Fix tests

* Change anonymous autoPlayGif default to false

* When gif autoplay is disabled, hover to play

* Add option to hide the timeline preview

* Slightly improve alt layout

* Add elephant friend to new frontpage

* Display "back to mastodon" in place of "login" when logged in on frontpage

* Change polling time to 3s

* Update ar.jsx

Updating some (ar) translation.

* Update ar.yml

Pushing some missing translation strings on ar.yml

* Create ar.jsx

* Preparing file for translation.

* Create ar.yml

* Preparing file for translation.

* Create simple_form.ar.yml

* Preparing file for translation.

* Create devise.ar.yml

* Preparing file for translation.

* Create doorkeeper.ar.yml

* Preparing file for translation.

* Update index.jsx

Preparing file for translation.

* Update mastodon.jsx

* Preparing file to translation.
* Correction thanks to @Taekiro
  https://github.com/tootsuite/mastodon/pull/1798#pullrequestreview-32924922

* Update settings_helper.rb

Preparing file to translation.

* Update application.rb

* Preparing file to translation.

* Update simple_form.ar.yml

* Update doorkeeper.ar.yml

* Update devise.ar.yml

* Update ar.yml

* Fix i18n-tasks unused issue (ar)

Remove unused translation strings

* Update application.rb

* Update ar.jsx

* Fix various issues with Arabic translation

* Fix duplication caused in merge
* Fix syntax error in devise.ar.yml
* Fix import error Duplicated incorrect import in mastodon.jsx
* Fix duplication error in locales/index.jsx

* Update ar.yml

* Update ar.jsx

* Update ar.yml

* Update ar.jsx

* Fix ar translation