[WiP] Add Hyperparameter Optimization

[naomi-simumba]

• Modified optimizer function for configurable inputs
• Switched from argparse to jsonargparse for input validation/class instantiation.
• Dropped the “evaluate” command
• Created a new command “iterate” to handle HPO/repeated experiments for benchmarking
• add callbacks
• update example configs for new optimiser format

Issues: #26, #25, #24

cc: @etienne-v