Add a new permission to allow usage of system dataloaders.

Shell delegation only delegates permissions/appops.
Need to add the permission instead of checking UIDs.

Bug: 168508924
Test: atest PackageManagerShellCommandTest PackageManagerShellCommandIncrementalTest IncrementalServiceTest PackageManagerServiceTest ChecksumsTest
Change-Id: If31980b698cdfef251ffdca400d641a79948019f
Merged-In: If31980b698cdfef251ffdca400d641a79948019f