By Pavel Polityuk and Max Hunder KYIV (Reuters) -With a blessing for its EU ambitions and a pledge of unwavering support from Britain, Ukraine vowed on Saturday to prevail against Moscow as it battled Russian assaults near a key eastern city and multiple locations came under shell and missile attack. European Union countries are expected at a summit next week to grant Ukraine EU candidate status following a recommendation from the bloc’s executive on Friday, putting Kyiv on course to realise an aspiration seen as out of reach before Russia’s Feb. 24 invasion, even if actual membership could ta…