Let configs define indicator elements that get shown but can't be edited and don't get saved

[Banane9]

Basically a dedicated way to add a DataFeedIndicator<T> (where T is string exclusively, afaik) to the pages.

Of course, these should update automatically whenever their underlaying value changes if they are linked to a config key. This part could be done with a component as well, perhaps, that passes through the update event and has a ToString func to generate the indicator text.

For indicators not tied to config keys, an interface could be defined that presents the indicators. The indicators would themselves have an interface shared with the indicator component, which defines the properties necessary for the indicator and the changed event to update the DataFeedItem visual.

Would make the most sense to build on top of #6 / #9

[Banane9]

This is now implementable by mod authors through their own ConfigKeyCustomDataFeedItems<T> components for DefiningConfigKeys and by implementing the ICustomDataFeedItems interface for ConfigSections.

Implementing some helper for it could be a consideration.