Custom Event Refactor `[AARD-2080]`

[rutmanz]

Task

AARD-2080

Symptom

Currently there are a bunch of custom event classes with inconsistent implementations that both make it harder to find events and make the whole system more verbose. Unsubscription is also often done incorrectly or not done at all

Solution

I introduced an EventSystem class that manages all custom events and has generic create, dispatch, and listen methods.

Verification

Go through and try and trigger the list of events found in EventDataMap and confirm that they still work as before. This PR should not affect functionality

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Before merging, ensure the following criteria are met:

• [ ] All acceptance criteria outlined in the ticket are met.
• [ ] Necessary test cases have been added and updated.
• [ ] A feature toggle or safe disable path has been added (if applicable).
• [ ] User-facing polish:
  • Ask: "Is this ready-looking?"
• [ ] Cross-linking between Jira and GitHub:
  • PR links to the relevant Jira issue.
  • Jira ticket has a comment referencing this PR.

[rutmanz]

(because other open PRs add new events in ways that won't necessarily show up as conflicts, I'll want to do one last check before this is merged)

[rutmanz]

Just merged dev and dealt with the conflicts