Deparse varchar and numeric casts without arguments.

[jcsjcs]

When no arguments were supplied when casting to varchar or numeric, deparse was returning ().
e.g.
CAST("name" AS VARCHAR(255)) or "name"::varchar were deparsed as "name"::varchar().

This change returns "name"::varchar in this case and does similar for numeric.

[lfittl]

@jcsjcs Good catch, thanks for the contribution!

[jcsjcs]

@lfittl A pleasure.