Replacement for gdbclient

 Differences between this implementation and the old one:
 1. Resolves symbols/gdb based on device information (lunch
    target is irrelevant)
 2. Works with downloaded from build-server symbols
 3. Does not require user to specify exe file - detects it automatically

Bug: 18208329

(cherry picked from commit 9b8e4b37)

Change-Id: I13ae2debb6e2d827b9aa55e93864b5d60c2bd32e