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
please rename the current test: 'has a default localized SIM indicator'
and rename the new one: 'has a custom localized SIM indicator'