[Feature request] Set percentage of demand satisfaction

[AquiloSpiritus]

There is not enough opportunity to set the percentage of satisfaction of demand (link). For example, if I want half of the demand to be satisfied by one recipe, 30% by the second, and 20% by the third (three alternative recipes with the output of the same resource). Or I want 30% of factories to be with one set of modules, and the rest with the second. This can be partly solved by fixing the number of plants, but the fix needs to be redone when scaling.