A written agreement to submit any existing controversy to arbitration or a provision in a written contract to submit to arbitration any controversy thereafter arising between the parties is valid, enforceable and irrevocable, except upon such grounds as exist at law or in equity for the revocation of any contract. This article also applies to arbitration agreements between employers and employees or between their respective representatives unless otherwise provided in the agreement; provided, however, that nothing in this chapter shall be construed to create any right to arbitration with respect to any controversy regarding the employment or terms and conditions of employment of any officer or employee of the Commonwealth.