Refactor the class viewer and level up dialog

[asacolips]

While working through the various enriched HTML bugs as part of version 1.7.2, I ran into a lot of difficulty with enriching the fields and content for the class viewer and level up dialog. There's a lot of really old code in there and it was over engineered in hindsight.

Acceptance Criteria

• Refactor the level up dialog to use pack indexes for better performance.
• Abstract the logic used for merging items from the world and items from the compendium in order to simplify things like enriching their HTML fields in one place.
• Move it into a separate application outside of the character sheet
• Other improvements as they become neccessary/apparent

[somnolik]

Hi! I want to coordinate efforts: I'd like to refactor DwActorSheet._onLevelUpSave so I can change the HP calculation more easily.

Context: I've been working on an Uncommon World module for the past week, and changing the HP formula so far involves subclassing DwActorSheet and overriding _onLevelUpSave with a slightly modified version, which isn't that pretty a solution, not easily maintainable.

I wanted to check if you're amenable to accepting PRs, and after seeing this ticket I also wanted to ask if I should wait for this refactor to be done before I start butchering refactoring _onLevelUpSave.

Cheers!

[asacolips]

Hi @somnolik! I'm definitely open to PRs for anything on the system. I don't have a specific timeline for when I'll start this refactor, but I do believe it will be the first thing I prioritize when I am actively working on new DW features again.

If you want to implement your override before the refactor is done, feel free to link to your override in a comment here and I'll add it as a checklist item to make sure you're notified before the eventual refactor goes out.