Wean statsd off batterystats: workchain, longPW

The tool that generates StatsLogInternal.java now includes the following
type of code, to accomodate WorkSources automatically.

    public static void write(int code, WorkSource ws, int arg2) {
        for (int i = 0; i < ws.size(); ++i) {
            write_non_chained(code, ws.get(i), ws.getName(i), arg2);
        }
        ArrayList<WorkSource.WorkChain> workChains = ws.getWorkChains();
        if (workChains != null) {
            for (WorkSource.WorkChain wc : workChains) {
                write(code, wc.getUids(), wc.getTags(), arg2);
            }
        }
    }

This will reduce a lot of code repitition for the StatsLog.write calls
in BatteryStats. Consequently, doing so will make it easier to remove
these StatsLog.write calls out of BatteryStats. We start in this cl with
LongPartialWakelock (as proof of principle).

Bug: 80308558
Bug: 80314737
Test: manual verification
Test: com.android.internal.os.BatteryStatsTests
Change-Id: Ibd28297345f4ab926dec01a89de0f1bfff9f8871