Use Episode IDs from the sync task response instead of our local ones

[bjtitus]

Uses the UDIDs of the episodes from the sync response instead of re-querying for the unsynced episodes. This fixes an issue where users with 2000+ episodes in a background sync could send the same episodes during background sync repeatedly.

• Adds a useSyncResponseEpisodeIDs feature flag in case we need to disable
• Adds duplicate method for marking episodes synced with their uuid instead of the local id
• Updates processServerData to use these uuids when handling the server response

Unit Tests

• Adds unit tests to test the new update behavior from the server response

To test

• Build and run the app
• Subscribe to some podcasts
• Add several episodes
• Mark several episodes as archived
• Refresh via the profile or kill and relaunch the app
• Make sure the sync occurs. You should see some logs in the console:

SyncTask: sending 6 changed items to the server

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.

[CookieyedCodes]

Will this help fix my issue Automattic/pocket-casts-android#628?

[bjtitus]

@CookieyedCodes I doubt it. How many subscriptions do you have? This would mostly affect large subscription counts where synced episodes routinely exceed 2000.

[CookieyedCodes]

I have 2111 feeds 😅,

[danielebogo]

It works!
@bjtitus QQ, do we want this in 7.78 or 7.77?

[bjtitus]

I initially targeted 7.77 but thought:

• It's a little late in the cycle for the full testing
• We don't have specific user reports that this is actually causing issues

But it is flagged, so I'm open to either.

[danielebogo]

@bjtitus I'm ok with 7.78