GRDB: Podcast Data Manager

[leandroalonso]

This is another PR that adds a GRDB layer for PodcastDataManager. As the previous one, this works by duplicating and adapting the code.

We're having discussions in the initial PR about having a more generic layer that can work with both. I'm pushing this PR just so we can test GRDB.

To test

1. Run the app
2. Open a few podcasts
3. ✅ Ensure everything works as usual

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 larger than 500 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

	1 Message
📖	This PR is still a Draft: some checks will be skipped.

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[pocketcasts]

📲 You can test the changes from this Pull Request in Pocket Casts Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Pocket Casts Prototype Build
	Build Number	pr2584-4ffdbde
	Version	7.79
	Bundle ID	au.com.shiftyjelly.podcasts.prototype
	Commit	4ffdbde
	App Center Build	Pocket Casts - Prototype Builds #41

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