Wordpress-android: Update Gradle plugin to 3.3.+

[aforcier]

As of this writing, 3.3.2 is the latest Android Gradle plugin. We should update the project to use it. However, at the moment updating to 3.3.+ generates some build warnings:

• [x] 'variant.getGenerateBuildConfig()' is obsolete
• [x] 'variant.getExternalNativeBuildTasks()' is obsolete
• [ ] 'variant.getJavaCompile()' is obsolete (2 instances)

The first warning can be resolved by using the new provider config for this Crashlytics task:

android.applicationVariants.all { variant ->
    variant.generateBuildConfig.dependsOn(generateCrashlyticsConfig)
}

to

android.applicationVariants.all { variant ->
    variant.generateBuildConfigProvider.configure {
        dependsOn(generateCrashlyticsConfig)
    }
}

The next warning requires the Fabric gradle plugin to be updated to support 3.3.+ and fix its internal warnings - this has already happened, we just need to update to io.fabric.tools:gradle:1.28.0 when we're ready.

The last set of warnings, and the ones without an easy fix yet for 3.3.+, come from the Bintray plugin used in a few of the subtrees (libs/utils and libs/analytics). The Bintray plugin needs to be updated for that, we'll want to check on that periodically: https://github.com/novoda/bintray-release/releases. (It would be nice if there was a way to ignore this part of the subtree Gradle build when building WPAndroid, since it's irrelevant to actually building WPAndroid - but I don't know of one offhand.)

Note that we can of course update to 3.3.+ whenever we want, they're just warnings - but they're pretty noisy and we may want to hold off a bit if we can until they can be addressed.

cc @jtreanor

[aforcier]

Note that apparently earlier Fabric plugins don't work at all with Gradle 3.3.+ - everything seems normal but the app can't reach Fabric (see https://github.com/woocommerce/woocommerce-android/pull/911).

So we should extra definitely not update to 3.3.+ without also updating our Fabric plugin version as outlined above.

[jtreanor]

Wow!

Thanks for the update. Perhaps we should accelerate looking at alternative crash reporting providers.

[stale[bot]]

This issue has been marked as stale because:

• It has been inactive for the past year.
• It isn't in a project or a milestone.
• It hasn’t been labeled [Pri] Blocker, [Pri] High, or good first issue.

Please comment with an update if you believe this issue is still valid or if it can be closed. This issue will also be reviewed for validity and priority (cc @designsimply).

[aforcier]

@oguzkocer I believe we can close this now, #12896 upgraded us past this to 4.0.1, and the main problem libraries (Crashlytics and Fabric) aren't used anymore, and I think the Bintray plugin has been updated. ccing you anyway in case you spot anything relevant in here to any new warnings you might have noticed.