[FEAT] Encapsulate localStorage values better

[aclist]

Browser

Firefox-based

Script manager

Tampermonkey

KES version

4.3.0-beta.53

Describe the feature

Currently, all mods store their settings at the top level of the localStorage, whereas MES internal settings and MES debugbar settings are more neatly nested in their own objects.

This creates kind of a mess of settings where the localStorage is polluted with a bunch of bare keys, which makes it hard to disambiguate non-MES cache from MES cache. It becomes a long list of mod names all at the root. It would be better to nest this under what is currently kes-settings, or its own dedicated area.

However, this would break backwards compatibility with parseLocalStorage(), which is used to serialize the localStorage into a backup file. So either some function to migrate old settings files to the new hierarchy would need to be added, or old settings files would have to be treated as deprecated under the new spec.