Add `checkIfEverythingIsTranslated` tasks

[StefMa]

We may want to add a new Gradle task that checks if all translations are complete. If any translations are missing, the task will fail.

We can use the /projects API for this by iterating over the languages and checking if the progress is at 100%. See Project Object and Retrieve a Project for more details.

(Alternatively, the progress_total might also be useful 🤓)

Why/Motivation?

Before running/building an Android app, you download the translation strings using the plugin. If there are missing strings, your build tool might throw an error, for example, due to Android Lint. However, by the time this issue is reported, some time has already been lost.

To prevent this, we could implement a convenient “pre-check” using a single API call.

Discussion Points

• Should we create a separate task for this check, or should it be included in the existing downloadTask?
• Do we want to expose an option via the extension, or configure the new task dynamically?

[juschmitt]

Voting for:

• included in the extisting downloadTask
• exposing an option via the extensions
• by default this pre-check is off

Keeps the api small as you really only have to call 1 task to download the strings.