Make histogram options configurable from `init` and `BufferedMetricsLogger` constructor

[Mr0grog]

In #64, options were added to histograms for changing the percentiles and aggregations that it generates. However, these have to be specified on each call to histogram(). If you want to adjust them for all metrics you send you have to a hacky workaround:

const metrics = new BufferedMetricsLogger();

const originalHistogram = metrics.histogram;
metrics.histogram = function (key, value, tags, timestamp, options = {}) {
    options.aggregates ||= ["max", "avg", "count"];
    options.percentiles ||= [0.95];
    return originalHistogram.call(this, key, value, tags, timestamp, options);
});

Instead, it would be better if you could:

const metrics = new BufferedMetricsLogger({
    histogram: {
        aggregates: ["max", "avg", "count"],
        percentiles: [0.95]
    }
});

I’m not tied to the name of the option (histogram), just that it has the same properties the options argument on calls to histogram does.