Grant permissions could be removed due to new Android Test rule

[Kisty]

Came across this rule which would mean that the Grant Permission control in TB might be redundant. https://developer.android.com/reference/android/support/test/rule/GrantPermissionRule

[drewhannay]

I was looking at that recently as well, but haven't had time to dig into it fully. I'm wondering if Test Butler's functionality is still different since it can grant permissions as a system level app, which maybe aren't grant-able via GrantPermissionRule? I'd want to do a deeper dive on this and understand any potential differences before we deprecate / kill the Test Butler feature.