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.

src/card-controller/microphone-manager.ts

@@ -146,7 +146,7 @@ export class MicrophoneManager {
       muted: this.isMuted(),
       forbidden: this.isForbidden(),
     };
-    this._api.getConditionsManager().setState({
+    this._api.getConditionStateManager().setState({
       microphone: this._state,
     });
     this._api.getCardElementManager().update();