LONDON (Reuters) – The European Union will keep all options on the table in terms of its response to Britain’s move to override some post-Brexit rules for Northern Ireland, Maros Sefcovic said on Thursday, when asked about the possibility of a trade war. The EU launched new legal proceedings against Britain on Wednesday after London published its new legislation, with both moves expected to take over a year to come into force. The EU could eventually review terms of the free trade deal it agreed with Britain. It has already thrown doubt on its role within the $99 billion Horizon Europe researc…