Update Russian translation (#2891)

* Add Russian translation (ru)

* Fix a missing comma

* Fix the wording for better consistency

* Update Russian translation

* Arrange Russian setting alphabetically

* Fix syntax error

* Update Russian translation

* Fix formatting error

* Update Russian translation

* Update Russian translation

* Update ru.jsx

* Fix syntax error

* Remove two_factor_auth.warning (appears obsolete)

* Add missing strings in ru.yml

A lot of new strings translated, especially for the newly added admin section

* Fix translation consistency

* Update Russian translation

* Update Russian translation (pluralizations)

* Update Russian translation