Wean statsd off batterystats: workchain (cp)

Modified cherry pick from master:
(cherry picked from commit d888df2b)
covering ag/4210168 and ag/4230692.

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.

Bug: 80308558
Bug: 80314737
Test: manual verification
Test: com.android.internal.os.BatteryStatsTests
Change-Id: Ied537a6195121f16ef49b6bccf58c8c31964909c
Merged-In: Ibd28297345f4ab926dec01a89de0f1bfff9f8871