Add the oils_obj:required="true" attribute to the IDL fields that are
actually required by the database. A required field is one that
derives from a base table column that has a "NOT NULL" constraint and does
not have a default value.
IDL objects that are virtual or read-only are skipped as are virtual
fields.
Fields that already have the oils_obj:required attribute set are not
changed, even if the fields do not meet our criteria for being
required.
Signed-off-by: Jason Stephenson <jason@sigio.com> Signed-off-by: Galen Charlton <gmc@equinoxOLI.org> Signed-off-by: Jane Sandberg <js7389@princeton.edu>