Validate packageName with AppOpsManager#checkPackage

Change the permission check for tethering to checkPackage. This avoids
having to create context as another user which is not supported when
running the networkstack from secondary user.

Bug: 375535923
Bug: 216524590
Test: atest TetheringManagerTest TetheringServiceTest
Change-Id: Ibc3abe9ec2eab5ec976c6a9cbc08e1552203ee5d
3 files changed