[#2299] Add replacement option for ItemChoiceAdvancement

[arbron]

Migrates the configuration.choices data structure on item choice advancement to be an object with a new replacement boolean. This indicates that players can replace a previous choice at that level.

The configuration app for ItemChoiceAdvancement has been modified into a three column layout to prevent it from getting too tall when there are a lot of choices such as for Warlock.

A data model has been added for item choice with a new replaced object that indicates which previous choice was replaced for each level. The previous choices are kept within the value.added structure to accurately track choices across levels. The flow UI will display replaced choices as crossed out and has a radio button next to other previous choices so players can choose which of them to replace.

Closes #2299