Add further tests for preequilibration and reinitialization

[dweindl]

From PEtab doc:

If a species ID is provided, it is interpreted as the initial concentration/amount of that species and will override the initial concentration/amount given in the SBML model or given by a preequilibration condition. If NaN is provided for a condition, the result of the preequilibration (or initial concentration/amount from the SBML model, if no preequilibration is defined) is used.

This is insufficiently covered by the current tests. Case 10 is closest, but no NaNs for species entries in the condition table are present.