Bug 990537 - [DSDS] Messaging. Apply Visual Refresh to DSDS scenarios r=schung

* use :before instead of :after so that we re not affected by building blocks
* add the sim indication back
* use the correct style for the sim indication
* move the dsds CSS to composer.css
* correctly center the counter and MMS indicators

(cherry picked from commit 1391064a106b66b02b0b7b9e7e43c9bc775ba586)

Conflicts:
	apps/sms/index.html

* adds an hacky property file so that we don't need a localization on v2.0
Merge pull request #21395 from julienw/990537-v2.0-dsds-refresh

Bug 990537 - [DSDS] Messaging. Apply Visual Refresh to DSDS scenarios