Scaling of targets

[EveCharbie]

For now, the target of a penalty involving scaled variables should be scaled by the user directly.
It would be easy to implement it for minimize_states, controls and parameters, but it is more complex for other penalties.
But we should still find a way to do it for the user, as it is super unintuitive.

[mickaelbegon]

Draft PR opened: #1080

The built-in parameter objective now evaluates scaled decision variables in physical units, including heterogeneous scalings with key="all". Standard state/control penalties were verified to already expose unscaled values, and their stale scaling TODOs were clarified.

Local focused suite: 15 passed.

@pariterre everything works locally; the draft is ready for review once CI confirms it.