Saint Petersburg, Dec.10 (ONA) ---- The National Museum and the Hermitage Museum in the Russian Federation signed three agreements yesterday in the Russian City of Saint Petersburg.    The agreements were signed by Jamal bin Hassan al- Mousawi, Director General of the National Museum, and Professor Dr. Mikhail Piotrovsky, Director General of the Hermitage and member of the Board of Trustees of the National Museum.    The first agreement includes the construction of a corner bearing the name of Oman in the headquarters of the ancient Winter ...