Support qualified wildcards in aggregates

[justinj]

Postgres allows this:

postgres=# select count(x.*) from x;
 count
-------
     1
(1 row)

Whereas Materialize does not:

materialize=> select count(x.*) from x;
ERROR:  wildcard in invalid position

The semantics, at least for count, appear to be the same as count(*):

postgres=# select count(x.*) from (values (null)) x;
 count
-------
     1
(1 row)