Add Arabic translations for OARS categories

As part of the parental controls feature in Endless OS, we purchased
Arabic translations for these strings from Gengo (via Transifex).

I'm not an Arabic speaker so I can't vouch for the quality of these
translations; and Transifex don't provide authorship information beyond
1 job for master in 4 minutes and 59 seconds (queued for 1 second)
Status Job ID Name Coverage
passed #203697