Add CTS tests for ApfCapabilities static APIs.

Add tests for getApfEtherTypeBlackList and getApfDrop8023Frames APIs.

Bug: 150640397
Test: atest CtsNetTestCasesLatestSdk:android.net.apf.ApfCapabilitiesTest
      on both of Q and R devices.
Change-Id: I06c5d84d7025420a1e45a953c8c7a5cc3c452e24