Move data structure to dataclasses

[clmould]

Thanks to @timothy-nunn's work in #4120, we can convert the remaining global data structures to dataclasses.

This will be split into several pull requests. Will convert all model variables first, then scan, numerics and globals after the next release.

• Move water use data structure to a dataclass #4120
• Support input's being set on new data structure dataclass #4154
• Implement Model ABC on all models #4146
• move costs 2015 data structure to dataclass #4153
• cs fatigue data class and setting up use of datastructure elsewhere t… #4173
• vacuum dataclass #4189
• Costs dataclass #4196
• First wall dataclass #4226
• Get var descriptions from new dataclass structure #4216
• Fwbs dataclass #4230
• Blanket dataclass #4237
• Convert structure data structure to dataclass #4236
• Convert times data structure to dataclass #4238
• Convert Reinke data structure to dataclass #4239
• convert ccfe hcpb to dataclass #4243
• Convert Pulse data structure to dataclass #4244
• Convert build data structure to dataclass #4247
• Convert primary pumping data structure to dataclass #4245
• Convert buildings data structure to dataclass #4249
• Constraint vars dataclass #4250
• Convert DCLL vars to dataclass #4251
• Convert current drive vars to dataclass #4252
• Heat transport vars dataclass #4253
• Convert IFE vars to dataclass #4254
• Convert pf coil vars to dataclass #4256
• Convert power vars to dataclass #4257
• Convert divertor data structure to dataclass #4258
• Convert stellarator vars to dataclass #4259
• Convert pf power vars to dataclass #4260
• Convert neoclassics vars to dataclass #4263
• Convert impurity radiation data structure to dataclass #4264
• Physics dataclass #4268
• tf coil var dataclass #4279
• Convert superconducting tf variables to dataclass #4281

Below are the data structure conversions that need doing. Will add to the PR list above when working on them

• Implement Model ABC on all models
• blanket_library.py
• build_variables.py
• buildings_variables.py
• ccfe_hcpb_module.py
• constraint_variables.py
• cost_2015_variables.py
• cost_variables.py
• cs_fatigue_variables.py
• current_drive_variables.py
• dcll_variables.py
• divertor_variables.py
• first_wall_variables.py
• fwbs_variables.py
• global_variables.py (leave for now)
• heat_transport_variables.py
• ife_variables.py
• impurity_radiation_module.py
• neoclassics_variables.py
• numerics.py (leave for now)
• pf_power_variables.py
• pfcoil_variables.py
• physics_variables.py
• power_variables.py
• primary_pumping_variables.py
• pulse_variables.py
• rebco_variables.py
• reinke_variables.py
• scan_variables.py (leave for now)
• stellarator_configuration.py
• stellarator_variables.py
• structure_variables.py
• superconducting_tf_coil_variables.py
• tfcoil_variables.py
• times_variables.py
• vacuum_variables.py
• water_usage_variables.py