(Reuters) -BT Group’s outgoing boss Philip Jansen has been approached about becoming the next chair of advertising group WPP, replacing Roberto Quarta, Sky News reported on Monday. Quarta has been the chairman of WPP, the British company, whose agencies include Ogilvy, since 2015. Last year, BT, Britain’s biggest broadband and mobile provider, appointed Allison Kirkby as chief executive to replace Jansen, effective from around the end of this month. BT had previously said Jansen would remain as CEO until Kirkby took over, and he would be available to support the handover until the end of March…