Make isDataEnabledForApn() a system api.

Test: atest TelephonyManagerTest#testIsDataEnabledForApn
Bug: 140763963
Merged-in: I816972df567dd210822edc30f9434a39c7815e46
Change-Id: I816972df567dd210822edc30f9434a39c7815e46
(cherry picked from commit 5d4e1921a562dc77712b925424181846746e9ad8)
1 file changed