Add fromBase64EncodedString to BpfDump

EthernetTetheringTest has parseMapKeyValue that decodes the string
encoded by BpfDump#toBase64EncodedString
Upcoming CL also wants to decode the encoded string.
So this CL renames parseMapKeyValue to fromBase64EncodedString and moves
to BpfDump with refactoring

Bug: 217624062
Test: atest NetworkStaticLibTests
Change-Id: I6ec302aaaa3e8779119cf153567cb032828f5daf
2 files changed
tree: 9b65230f72db6d297a75a6eb3f32473e157ccae5
  1. staticlibs/