Consider fluid expansions through iteration not rewrites

[kayagokalp]

Currently we are using rewrite rules to create new fluids out of existing ones. Basically we insert only the initial fluid after doing that we are rewriting it to insert new ones until. Equality saturation is running better once we have rules that are making things simpler, not expanding them as we can do acylic egraphs etc to speed up things. Also it is easier to reason about so it might make sense to initially insert all the possible fluid concentrations (with limited scope)