Rename StatsD/bin to Statsd/statsd

statsd is a more intuitive name for this, as it is the files for the
stats daemon. It also matches the previous structure of
frameworks/base/cmds/statsd.

There may be some confusion between StatsD (in packages/modules/StatsD)
and the inner statsd. The difference is that StatsD is the name of the
apex, containing statsd but also the supporting libraries and jars. The
lowercase statsd is for statsd the daemon.

Test: m
Bug: 182597781
Change-Id: Ibb065d64be3775c699583215f7f376a1a5492ac1
212 files changed