IsEqualStateTrigger with Enum throwing FormatException at runtime

Bringing this issue from [here](https://github.com/CommunityToolkit/Labs-Windows/issues/216#issuecomment-1542604878)

I've discovered this while using `SettingsCard` and changing it's `ContentAlignment` property at runtime by editing XAML.
The `SettingsCard` uses the trigger like this:
```xaml

```

When I set that property before running the app, it works as it should.
But when I live edit it, it doesn't work and logs `FormatException`.

I found it fails here:

Two more notes:
- I didn't try binding it somewhere
- I'd say this might be occurring in other triggers too, didn't test

I'm running WindowsAppsSDK 1.3

IsEqualStateTrigger から始め、Windows App SDK 1.3 を使用して実行時に XAML の値を変更し、SettingsCard ContentAlignment のシナリオを再現します。FormatException を発生させる enum 変換を追跡し、他の state triggers でも同じ問題が発生するか確認します。enum 値をライブ編集しても例外がログに記録されず、trigger が正しく応答すれば完了です。

索引モデルが issue の本文から書いたものです。