Add KeyValuePairs support for modules.

Add KeyValuePairs support to StatsLog autogen for modules.

Bug: 147674597
Test: m
Test: fastboot flashall
Test: adb logcat "*:S statsd:*" and inspect KeyValuePair atoms.
Test: statsd_testdrive 83
Change-Id: Ie40ea52fde494ec11da6b73f430c7a112711b55b