Update simple_form.ar.yml (#2908)

Update simple_form.ar.yml (#2908)

* Update simple_form.ar.yml

Added missing strings that were introduced to simple_form.ar.yml and completing translation.

* Create confirmation_instructions.ar.html.erb

* Create confirmation_instructions.ar.text.erb

* Create password_change.ar.html.erb

* Create password_change.ar.text.erb

* Create reset_password_instructions.ar.text.erb

* Create reset_password_instructions.ar.html.erb