[App Clips] Add error empty state for App Clip and podcast latest episode fallback

[danielebogo]

📘 Part of: #2549

This PR replaces the Alert with an empty state for when the App Clip can not handle a URL.

Also this PR updates the way we load the URL:

1. it checks if there's podcast data
2. if it is we try to load the episode if the data exists
3. if the data doesn't exist we try to load the latest episode so the user at least play something
4. if the app clip fails at any moment we show the error empty state and not the alert

Light	Dark

To test

• In Xcode Select the App Clip scheme
• Edit the scheme and the appClipInvocationURLString with https://pca.st/hiddenbrain
• Run the App Clip target
• Confirm it plays the latest episode
• Modify the appClipInvocationURLString with https://pca.st/episode/2fd294d4-9c85-4401-b3b2-ea54b81cf54f
• Confirm you see the specific episode
• Modify the appClipInvocationURLString with https://pca.st/aaaaa
• Confirm you see the empty state and the banner shows quickly

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 7.84 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

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[SergioEstevao]

Working great!