Add `Model.simulate`

[dweindl]

In the next major release, we might want to replace amici.runAmiciSimulation by something shorter. Just amici.simulate or Model.simulate (more coherent with JAXModel.simulate_condition). Open for other suggestions.

[dweindl]

Maybe this should be planned in combination with #2845 to come up with a more convenient API, in particular for interactive use. See also the discussion in #931.

[dweindl]

For a start, because runAmiciSimulation and runAmiciSimulations will anyways be renamed as part of #887, I'd rename them to simulate and simulate_multiple (or simulate_condition and simulate_conditions? or simulate and simulate_conditions? other suggestions?).

I'd add them to Model in Python, because that's more convenient for interactive use, but keep them as free function in C++, for now.

[dweindl]

Closed by #2963