Display specific, user-friendly error message when upload categories search API call returns an error

[ted-gilbert]

Description (required)

Fixes #5225

What changes did you make and why?

Modified the error handling in UnsuccessfulResponseInterceptor.intercept so that MwIOException is raised for non-suppressed errors. The error code and details are parsed into a MwLegacyServiceError object, which is attached to MwIOException.

Added a method, showErrorDialog(String) to UploadCategoriesFragment and CategoriesContract which displays an AlertDialog stating that an error has occurred while loading categories and showing a specific error message.

Added handling to CategoriesPresenter in onAttachView and onAttachViewWithMedia which displays an alert with the specific MediaWiki API error when the categories search throws MwIOException.

Tests performed (required)

Tested betaDebug on Medium Phone with API level 35.
Tested prodDebug on Medium Phone with API level 35.

Screenshots (for UI changes only)

Need help? See https://support.google.com/android/answer/9075928

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[github-actions]

✅ Generated APK variants!

• 🤖 Download betaDebugAPK
• 🤖 Download prodDebugAPK

[nicolas-raoul]

Looks good to me! I did not go as far as voluntarily trigger an error, but at least it works for successful search and category not found. 🙂