Nik Everett 42be39177b
Remove ceremony declaring aggs (backport of #53990) (#54099)
This removes some more ceremony when declaring agg parsers. You no
longer need a static `parse` method, instead you can just make the
`PARSER` public in most cases.

There are still a few aggs with the `parse` method, but those `parse`
methods are a little more complex to untangle.
2020-03-24 12:29:52 -04:00
..