Oracle DDL handle missing check constraint name

[StandardDdlParser] isTableConstraint already handles PK, FK and UNIQUE constraints with optional constraint names, but only handles CHECK with constraint name present.

according to Oracle docs (https://docs.oracle.com/cd/B28359_01/server.111/b28286/clauses002.htm#CJAGIICD)

• "... CONSTRAINT sth_name CHECK (check expr) ..." is handled correctly
• "... CHECK (check expr) ..." is NOT handled correctly

If the same applies to other DB dialects this should be fixed in StandardDdlParser otherwise the method should be overloaded in OracleDdlParser.