DupuytrEn Treatment EffeCtiveness Trial (DETECT): a protocol for prospective, randomized, controlled, outcome assessor-blinded, three armed parallel 1:1:1, multicenter trial comparing efficacy and cost effectiveness of collagenase clostridium histolyticum, percutaneous needle fasciotomy and limited fasciectomy as a short and long term treatment strategy in mild or moderate Dupuytren’s contracture