Compute log-prior and unnormalized log-posterior in `simulate_petab`

[dweindl]

So far, only the logliklihood is computed in simulate_petab.
Extend that to additionally include the log-prior and unnormalized log-posterior.
With PEtab-dev/libpetab-python#329, this will be easy to do via libpetab.

[dweindl]

For PEtab v2, there is now also a test case with priors. Extend the checks here accordingly.