Add per media partial settings

[Yoooi0]

"Partial" manager for partial settings/scripts (funscript metadata)?. Button to save current changes to <media name>.config.json.partial. Needs to only save changes by comparing with main saved config. Button to remove partial config. Button to import/apply partial config. Some settings can't be in partials, like output target/media source tabs, so probably have to restructure config saving to full config/partial config.