feat: add support for create operator

[cvng]

What kind of change does this PR introduce?

add support for create operator

What is the current behavior?

panics

What is the new behavior?

parser returns

View log

```rust DefineStmt { kind: ObjectOperator, oldstyle: false, defnames: [ Node { node: Some( String( String { sval: "+", }, ), ), }, ], args: [], definition: [ Node { node: Some( DefElem( DefElem { defnamespace: "", defname: "procedure", arg: Some( Node { node: Some( TypeName( TypeName { names: [ Node { node: Some( String( String { sval: "plusfunc", }, ), ), }, ], type_oid: 0, setof: false, pct_type: false, typmods: [], typemod: -1, array_bounds: [], location: 48, }, ), ), }, ), defaction: DefelemUnspec, location: 36, }, ), ), }, Node { node: Some( DefElem( DefElem { defnamespace: "", defname: "leftarg", arg: Some( Node { node: Some( TypeName( TypeName { names: [ Node { node: Some( String( String { sval: "int4", }, ), ), }, ], type_oid: 0, setof: false, pct_type: false, typmods: [], typemod: -1, array_bounds: [], location: 84, }, ), ), }, ), defaction: DefelemUnspec, location: 74, }, ), ), }, Node { node: Some( DefElem( DefElem { defnamespace: "", defname: "rightarg", arg: Some( Node { node: Some( TypeName( TypeName { names: [ Node { node: Some( String( String { sval: "int4", }, ), ), }, ], type_oid: 0, setof: false, pct_type: false, typmods: [], typemod: -1, array_bounds: [], location: 117, }, ), ), }, ), defaction: DefelemUnspec, location: 106, }, ), ), }, ], if_not_exists: false, replace: false, } ```

Additional context

waiting for the correct design in #72

[cvng]

@psteinroe now that #72 is merged this one is also ready for review