fix: change default collation allowance

[Climax777]

Make provision for C_COLLATION_OID and POSIX_COLLATION_OID, which are also built-in types.

I'm not 100% sure what the impact will be, but everywhere specifically DEFAULT_COLLATION_OID was used, the other two are allowed now as well.

This fixes #169 and pushes down ObjectID queries for all columns.