By Alexander Marrow and Dimitri Rhodes LONDON (Reuters) - Ben & Jerry's seized the spotlight on Unilever's ice cream unit on Tuesday to renew a call for its own spin-off ahead of a planned listing of the business in November after years of clashing over the U.S. brand's vocal position on Gaza. As the new Magnum Ice Cream Company presented its growth plans on its first investor day ahead of the listing, the stand-off highlights one of the challenges for the new firm as it looks to rev up growth and win ov ...