[FIX] Emoji rendering on last message

[FIX] Weird rendering of emojis at sidebar when `last message` is activated

[FIX] Emoji size on last message preview

- The function returns one of three values:
  1 - The user's preference (user.settings.preferences.<preference>)
  2 - The default system setting value (Default_User_Preferences_<preference>)
  3 - A default value passed as argument to the function

- Besides the introduction of the helper function:
  - Removes unused preferences (user.settings.preferences.unreadRoomsMode, user.settings.preferences.audioNotificationValue) and creates migration script (v105)
  - Implements some simple tests

as in #6046 the package files should be located under a client or server folder

and a hardcoded string

and a hardcoded string

* rocketchat:postcss parser and cssnext implementation

* convert forms, keygrames and reset to cssnext

* convert rtl to cssnext

* convert base.less to cssnext

* convert base.less to cssnext

* fix * selector

* try to fix tests

* add css browser support

* remove duplicated test

* remove duplicated get

* skip fileupload test

* fix tests

* skip fileupload tests

* Try to fix tests

* try to fix the test

* test

* vai que vai

* fix wrong commit

* try again

* try some more

* try to fix tests

* skip the failing tests

* skip last test

* fix stylelint

* stylelint

* fix height calc

* skip sweetalert tests again

* skip more sweetalert tests

* Add eslit rule `one-var`

* ESLint add rule `no-var`

* Add ecmascript package to all packages

* Use ecmascript package for server and client on saml package

* Fix compilation

- Update sprite css
- Change render emojis logic