Refactor equations analyses

[tim-at-topos]

All the mess in catlog-wasm/src/analyses.rs (made worse in #1090) should be refactored (to make it not specific to mass-action) and pulled out somewhere more sensible. This will have some overlap with addressing #1096.

Once #965 has been merged, we should possibly consider whether we really need both ODEResult and ODEResultWithEquations, since all ODE analyses should be able to come with equations.

[tim-at-topos]

possibly also affected by #1105