Skip the tests relevant to bpf if bpf is not supported

Skip the test cases related to bpf functionalities if the device
does not support bpf.
ResolverTest#BlockDnsQueryWithUidRule
ResolverTest#EnforceDnsUid
ResolverTest#BlockDnsQueryUidDoesNotLeadToBadServer
ResolverMultinetworkTest#DnsWithVpn

Bug: 180574161
Bug: 182085418
Test: atest
Test: forrest, resolv_integration_test can pass in non-bpf device
Change-Id: Ib2d14703187d0f83bb604b4f4434fde51e6a380b