activate sort for column_def

[DivadNojnarg]

Fix #17. @olajoke For now, we can activate sort by passing sort = TRUE in column_def(). There is a more advanced usage which requires to pass it with JS (like in DT, reactable, ...). This does not work yet, as I was unable to get it working properly:

{
      field: "no",
      caption: "no",
      width: 50,
      // define custom sort logic
      sort(order, col, grid) {
        const compare =
          order === "desc"
            ? (v1, v2) => (v1 === v2 ? 0 : v1 > v2 ? 1 : -1)
            : (v1, v2) => (v1 === v2 ? 0 : v1 < v2 ? 1 : -1);
        records.sort((r1, r2) => compare(r1.no, r2.no));
        console.log("sorted:", records);
        grid.records = records;
      },
    },
    {
      field: "name",
      caption: "name",
      width: 200,
      // use default sort logic
      sort: true,
    }

As a side note, I removed the toJSON here as it does not seems useful and causes issues if we have to pass JS callbacks with the JS function.