Dario Panici

Partially addressed by #1806 , only remaining is to show an example use inside advanced optimization notebook of ObjectiveFromUser and GenericObjective

For the requested example of having an objective to target: 0.81 < iota_ax < 0.82, and 0.96 < iota_edge < 0.98 The preferred way to do this within DESC would...

Specifically this is referring to the [partial_sum fxn ](https://github.com/PlasmaControl/DESC/blob/958b87542c1579ea5562d22be895308dc93959ad/desc/equilibrium/coords.py#L400`) and to the [map_clebsch_coordinates](https://github.com/PlasmaControl/DESC/blob/958b87542c1579ea5562d22be895308dc93959ad/desc/equilibrium/coords.py#L457) which uses it, which is used currently inside a few objectives but is not publicly documented

For tests, two examples to modify with the new input structure - https://github.com/PlasmaControl/DESC/blob/587fd8526578a74602c868fce85e843f131c4795/tests/test_examples.py#L1831 - https://github.com/PlasmaControl/DESC/blob/587fd8526578a74602c868fce85e843f131c4795/tests/test_linear_objectives.py#L984

> * The setter functions in `_Objective` will have issues with pytree inputs. Would it make sense to add specific setters in `_CoilObjective`? Actually question here: if we always in...

> Yep, the issue would just be if someone sets the target/bounds/weights after initializing. If additional checks/logic would be helpful, I can add that. I see, I think that yes...

hm weird that CI cannot run the noteboook due to memory, try adding `jac_chunk_size=5` to the `LinkingCurrentConsistency` constraint. Also I cannot tell bc the docs did not build but did...

looks like maybe you had dark mode on or something? Never seen that before haha but it does make the coils difficult to see here

We will keep as draft until we implement a use case (either on this PR or on a PR pointed to this one)

- Vmap changes could still be put into master, make new PR for this