Added 'oneway' flags on AIDL where appliable.

Not only if fixes warning about outgoing transactions from system_server
not having the FLAG, but it fixes system crashes when the service
doesn't behave well (for example, if it does not call super.onCreate()
on onCreate().

BUG: 31001899
Test: manually built and ran it

Change-Id: I829ee501edb84bd02a60e8df92f9a0e0d2157887