updateColumnWidth(id, width) {
    let column = this._columns.find((x) => x.id === id);
    let previousWidth = column.width;
    column.width = width;
    let last = this._columns[this._columns.length - 1];
    let lastColumnWidth = last.width + previousWidth - width;
    last.width = lastColumnWidth;
    this.processColumns();
  }
Method that updates a specific column's width.
One column's width change will affect the last column's
width. Calling this will result in an updated `columns`
array.

@method updateColumnWidth
@param {String} id The column's id
@param {Number} width The column's new width