By Valentina Za and Andrea Mandala MILAN (Reuters) -France’s Credit Agricole has become the single largest investor in Banco BPM after buying a 9.2% stake, raising the prospect of a full takeover bid and sending shares in Italy’s third-largest lender sharply higher. The move increases the French group’s exposure to its main foreign market, where it has been playing an active role in ongoing banking consolidation. While Credit Agricole said it had not sought supervisory approval to go above 10%, analysts pointed to the gradual stakebuilding since 2018 that preceded its $1 billion takeover of re…