escapingStringDelimiters(string) {
    return (string || '').replace(/'/g, "''");
  }
Returns its argument with single quotes escaped, so it can be included into a single-quoted string.

For example, it converts "has'quote" to "has''quote".

This assumes QUOTED_IDENTIFIER ON so it is only ' that need escaping,
never ", because " cannot be used to quote a string when that's on;
otherwise we'd need to be aware of whether the string is quoted with " or '.

This assumption is consistent with the SQL Knex generates.
@param {string} string
@returns {string}