Refactor investment code to calculate `CoefficientsMap` upfront

[tsmbland]

... we should pass prices to the investment algorithm, then calculate CoefficientsMap for each asset upfront using these prices, then continue with appraisal. I think that's better than how we currently do it as we're calculating CoefficientsMap multiple times when (I don't think) it will change.

Originally posted by @tsmbland in #882 (comment)

See discussion in #882 for more detail