By Andrew Callus LONDON, Dec 2(Reuters) - BP will outline growth plans for its oil and gas production arm on Monday in its first strategy update since striking a series of deals aimed at getting its Russian and U.S. operations back on track. Like all top investor-owned western oil firms, BP is struggling to increase output and reserves in an era when nations guard their resource wealth jealously, and spending ever more billions of dollars to find new supplies and develop them. The Un