It is the express intent of the General Assembly in enacting the provisions of this chapter to provide for alternative methods for annexing or deannexing an area or areas into or from the corporate limits of a municipality. Except as otherwise expressly provided in this chapter, no provision of this chapter relating to annexation or deannexation by any such alternate method is intended to or shall be construed to in any way restrict, limit, or otherwise impair the authority of the General Assembly to annex or deannex by local Act.