By Amanda Ferguson BELFAST (Reuters) -British Prime Minister Rishi Sunak met with the main political parties in Northern Ireland on Thursday in his first visit to the region since taking office in October. The talks were expected to focus on a dispute over post-Brexit trade rules governing the region, which has blocked a normalisation of relations between Britain and the European Union and plunged local politics into crisis. Following a lengthy stalemate, Britain and the European Union resumed talks in October on how to fix problems relating to the Northern Ireland protocol, which introduced c…