[FR] Improve config parsing using only yaml files, no custom loading

[james-alvey-42]

Is your feature request related to a problem? Please describe.
Currently config loading and addition of new options is very complicated, and hard for a user to add a new one.

Describe the solution you'd like

• Load directly from yaml files with simple loaders
• No custom data management from config, direct output of yaml loader
• Default settings management inside peregrine simulator and network to enable simple run scripts or quick tests without need for a global config
• Better management of parameters (e.g. no split between parameters)
• Better management of priors
• Remember to rename waveform_apprx to match bilby naming convention