refactor: Significantly refactor how conditions work internally (#1886)

- Much improved API cleanliness and testability to allow further
extensibility in future
 - Simplified code in `live` view

This technically contains a small change in how overrides work in the
`live` view. Since that change is _closer_ to the documentation, and
since this is likely to be rarely used, this is not considered a
breaking change. Previously, overrides for a given live camera would
always render _as if_ that camera was selected, vs was actually
selected. Now, overrides will only apply in the live view when the
camera is _actually_ selected. If this is an issue for you in practice,
lets discuss.

tests/conditions/state-manager-via-event.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it, vi } from 'vitest';
+import { mock } from 'vitest-mock-extended';
+import { ConditionStateManager } from '../../src/conditions/state-manager';
+import {
+  ConditionStateManagerGetEvent,
+  getConditionStateManagerViaEvent,
+} from '../../src/conditions/state-manager-via-event';
+
+// @vitest-environment jsdom
+describe('getConditionStateManagerViaEvent', () => {
+  it('should dispatch event and retrieve state manager', () => {
+    const element = document.createElement('div');
+    const stateManager = mock<ConditionStateManager>();
+
+    const handler = vi.fn().mockImplementation((ev: ConditionStateManagerGetEvent) => {
+      ev.conditionStateManager = stateManager;
+    });
+    element.addEventListener(
+      'advanced-camera-card:condition-state-manager:get',
+      handler,
+    );
+
+    expect(getConditionStateManagerViaEvent(element)).toBe(stateManager);
+  });
+
+  it('should dispatch event and retrieve state manager', () => {
+    const element = document.createElement('div');
+
+    const handler = vi.fn();
+    element.addEventListener(
+      'advanced-camera-card:condition-state-manager:get',
+      handler,
+    );
+
+    expect(getConditionStateManagerViaEvent(element)).toBeNull();
+  });
+});