See https://www.postgresql.org/docs/9.5/functions-aggregate.html for descriptions of what these do. Note that they only accept bools, not values that can be cast to bools
https://github.com/MaterializeInc/materialize/pull/8057 was an original attempt to implement this, but appears to be inefficient?
Note that these agg functions have kindof odd semantics, that do not match
mz_any (which can be too general: https://github.com/MaterializeInc/materialize/issues/15805), or generally how
count(*) FILTER's work: