CHAR_LENGTH not supported in ALASQL

[efbenson]

Building Experience Builders to use our koop layers, we have run into queries that include CHAR_LENGTH. Koop throws errors as it is not supported by ALASQL per https://github.com/AlaSQL/alasql/wiki/SQL-keywords

TypeError: alasql.fn.CHAR_LENGTH is not a function

I was able to work around it with patching in a custom function in @koopjs/winnow/src/filter-and-transform/filter-and-transform.js

sql.fn.CHAR_LENGTH = function(value) {
  if (value === null || value === undefined) {
    return null;
  }
  return String(value).length;
};