Support setting / getting named joint states

[sea-bass]

There should be an API to set/get joint states by name by storing them in dictionaries.

Additionally, this could support different groups, as well as loading the states from SRDF (which Pinocchio sort of already has).

[henrygerardmoore]

I'm going to try this out :)

[sea-bass]

Awesome, looking forward to it!

Although it might make things easier to start with an attempt at #56, since ideally named states could pertain to a subset of joints.

This probably won't be super straightforward, but I suspect it requires a wrapper around the models to manage joint indices and the like. I left a blank placeholder for something like this in https://github.com/sea-bass/pyroboplan/blob/main/src/pyroboplan/core/planning_context.py, if you wanna give it a try and fill it partially?

[henrygerardmoore]

Yes, I'd like to give that a try! I actually already finished a super rudimentary setting/getting joint states API which is basically a dict wrapper with some added convenience functions + an example (didn't take into account any joint groups), but it makes sense that starting with joint groups should come first. I'll maybe make a draft PR of that so you can just give it a quick look over and see if it captures your intent with this issue, and then update it once I've made an attempt at #56. Does that seem like a good approach?

[sea-bass]

SGTM, thanks @henrygerardmoore!