By Michael Roddy LONDON (Reuters) – It’s happened very fast for soprano Catherine Foster, who was a midwife before she became a singer and this week will be the first Englishwoman to sing Brunnhilde for Wagner’s “Ring” cycle at the Bayreuth Festival, in the composer’s 200th birthday year. Foster, a native of the mid-England city of Nottingham who made a drastic career switch in the mid-1990s, plays the warrior goddess who lets the gods burn but saves humanity in a new production by radical Berlin theatre director Frank Castorf. …