Tag posts and comments with language (fixes #440) (#2269)

Tag posts and comments with language (fixes #440) (#2269)

* Tag posts and comments with language (fixes #440)

* Untangle PostView tests

* Implement test for PostView language query

* Store languages directly in database

* finish moving languages into db, it compiles

* update post_view

* serde skip Language.id field

* add local_user_language table, other changes suggested in review

* add code for local_user_discussion_language_view

* Remove unnecessary clones in db view converteres

* Fixing up some table and join issues.

* Clearing the current languages.

* Fix formatting.

* update user languages in single transaction

* proper test for user language queries

* Some fixes for all / missing user languages. (#2404)

* Some fixes for all / missing user languages.

* Adding back in transaction.

* fix test

Co-authored-by: Dessalines <tyhou13@gmx.com>
Co-authored-by: Dessalines <dessalines@users.noreply.github.com>