This commit updates the VCN code to use CarrierConfig to
store the restriction policy configuration, and notify
policy listners when the CarrierConfig gets updated.
Bug: 239104955
Test: atest FrameworksVcnTests(new tests)
Test: atest CtsVcnTestCases
Test: manually verified by overriding carrier configs
Change-Id: Iaeb1871b7d9f5c3d1b4e5ec24cfbf79eea58256f