WESTFIELD — With its historic bell tower, wide front bays and iconic tiled roof, the Westfield firehouse has served as a definitive community landmark for almost 150 years. After decades of careful renovations and creative space-saving solutions, however, the department has finally outgrown its longtime home. Now, as the community prepares for a wave of new construction, the future of the firehouse and of the department itself has become the subject of renewed debate as local officials work to find the best road forward.