introduce some intermediate level parameters

[baggepinnen]

This PR depends on:

• fix: check scope when discovering variables from equations SciML/ModelingToolkit.jl#3072
  • new release

Note to self: If one of the errors

 The initial condition for parameter body₊body₊m isn't provided.

car₊body₊m cannot be converted to Float64. Please provide a default value for the symbolic variables.

appear, it might be due to parameters being forwarded straight through a component like BodyShape using the kwargs..., and the default for the parameter in the inner body does not find the corresponding parameter in the ParentScope (BodyShape). By introducing the same parameter in the BodyShape, this is resolved.

It can also happen if pars aren't provided to the ODESystem constructor in the component that defines them.