Select metrics with a configuration file

[SuperQ]

The current simple metric prefix selector works, but makes it difficult to do aggregation selection.

Rather than a simple command line flag, a configuration file will make it easier to combine different metrics prefixes with different aggregators.

[yyzh1]

hello @SuperQ , I wonder whether this is still being worked on? I recently had to add aggregation for my own use case and wonder if I can also help to add this to the project. thanks!