Missing initialization of discrete-to-continuous communication parameter

[baggepinnen]

The PR #2355 exposes a problem with the initialization of the d2c_view of the parameter vector for systems with discrete state variables. I think (but am certainly not sure), that it might be sufficient to run the line

copyto!(d2c_view, d2c_obs(disc_state, p, t))

upon initialization of the problem to correctly initialize p, but it's not clear to me how to actually do this in any convenient way. One potential way would perhaps be to let generate_discrete_affect output also an initialization function? @YingboMa