Aggregations: Add better validation of moving_avg model settings

[polyfractal]

Adds proper validation of the settings passed to a moving average model. You will now get an exception if you try to pass an unknown, non-whitelisted parameter to a model, instead of silently dropping it on the floor.

The only point of contention is that I added a settings() method to the MovingAvgBuilder, so that this could be tested, and perhaps allow users to specify all the parameters in one pass. This is opposed to specifying all the parameters on the model builder itself, which only allows you to specify applicable params.

So on one hand the settings() param more closely mimics the REST api and allows convenience, on the other hand it provides a small foot gun.

@colings86 If you could take a peek at this when you get time, it'd be swell. No rush, pretty low priority ❤️

[colings86]

I think this should be a ParseException instead of an IllegalArgumentException. This would be in line with what we do elsewhere in the codebase (such as in the mapper parsers where any left over parameters after parsing is done are throw in a MapperParsingException).

[colings86]

@polyfractal left a small comment but otherwise it looks good