Whenever a governmental unit is authorized by applicable law to issue bonds without referendum pursuant to authority granted or mandate imposed to pay for some public purpose or facility, the public corporation may add to the estimate of costs and include in the authorized amount for such bonds and pay from bond proceeds an amount to provide for expenses of issuing such bonds, including underwriter’s spread and costs of bond insurance or other credit enhancement, and also an amount to pay capitalized interest and provide a reserve fund as otherwise permitted by this Act.