Clatd: add dump raw BPF map support

Add dump raw BPF map command to connectivity service. The result will
be encoded as base64 strings. This is a preparation for Clatd's tests.

Usage:
    dumpsys connectivity {clatEgress4RawBpfMap|clatIngress6RawBpfMap}

Bug: 285124667
Test: test with MtsEthernetTetheringTest#testTetherClatBpfOffloadUdp
      which will be uploaded in a separated CL
Change-Id: I02c8efadb1c4b861d9bf6168667816b13412dc75
5 files changed