Add BpfInterfaceMapUpdater#getIfNameByIndex

Upcoming CL uses this to dump stats bpf map

Bug: 217624062
Test: atest com.android.server.net.InterfaceMapValueTest
com.android.server.net.BpfInterfaceMapUpdaterTest

Change-Id: I5454b6abbd9d84cb7e1dccaaa772d66726cfe3d0
4 files changed