Add function for generating ensemble when gapfilling draft model for biomass production without biolog data

[Tjmoutinho]

There is currently a way to generate an ensemble using biolog data, however there is no function for just creating an ensemble draft based on one condition. Additionally, this function would benefit from including an argument for including weighted inclusion of reactions based on reaction likelihoods. This could be solved by adding arguments to the existing biolog gapfill function ('_continuous_iterative_binary_gapfill').