Copy necessary data from Jtor_universal to avoid deepcopying the whole object

[timothy-nunn]

Extracts important information from the Jtor_universal class into a seperate dataclass for use as ._profiles. This removes the need to deepcopy the profile.

[nicamo]

This is great @timothy-nunn! And you're right, limiter_handler is static and does not need to be updated. (I'll correct myself here if needed, but) I believe it's only the 'direct' attributes of profiles that actually need to be copied (e.g. the critical points .opt and .xpt, the plasma currents distribution .jtor, the defining parameters alpha beta etc -- the latter ones in case of evolutive solves only). It should be possible to just 'manually copy these across'

[timothy-nunn]

Hey @nicamo

I have updated this PR to an alternative idea where instead of deepcopying (and having to make deepcopy implementations) we have a data class of ProfileData (there is probably a better name) that stores the data needed in the _profiles attribute. This does not depend on dubious deepcopy implementations and is more explicit about what is being copied. It also has the added benefit that we significantly reduce the amount of stuff copied to only what is needed*.

*what is needed within the main code. There may be scripts I do not know of that this breaks.

[timothy-nunn]

Closing because #43 implements this same fix in a better way, plus removes more deepcopies