All bonds, notes, contracts, agreements and obligations of housing authorities heretofore issued or entered into relating to financing or undertaking (including cooperating with or acting as agent of the federal government) in the development or administration of any project to assure the availability of safe and sanitary dwellings for persons engaged in national defense activities, are hereby validated and declared legal in all respects, notwithstanding any defect or irregularity therein or any want of statutory authority.