Add progress tracking to gradle package

[clabe45]

One way to implement this would be to return a generator, yielding the current progress as a percentage every time gradle prints a progress update.

We will most likely need to pass --console=plain to Gradle to make its output machine readable.

To calculate a percentage, we could parse the Gradle tasks by doing a dry-run and use that as the total task count.

Once this issue is completed, the next step is to use this feature in the main cli package (shulkr).