This bug occurred when arguments were read for the GROUP BY sorter — all
arguments were incorrectly resolved to the first column. Added tests
confirm that aggregates now work correctly both with and without the
sorter.
`BTreeTable::to_sql` makes us incompatible with SQLite by losing e.g. the original whitespace provided during the CREATE TABLE command.
For now let's fix our tests by regex-replacing every CREATE TABLE in
the entire repo to have exactly 1 space after the table name in the
CREATE TABLE statement.
