Bug 1096330 - [Messages][RTL] Correctly handle recipient pills. r=julien

* _Why do we need ```text-align: right```_? 

  Only for the cases when currently editable recipient looses focus but not yet assimilated: case №1 - when we tap on thread-container - I guess will it'll be fixed eventually, case №2 - when we use screen reader, eg. single touch on message input steals focus from currently editable pill, but doesn't yet give it to message input.

* _What is the visual impact_?

  Once focus is lost, ```flex-grow``` returns and because of ```dir=auto``` LTR\RTL name would be always left\right aligned in both LTR and RTL document.