Log progress when uploading an app to Browserstack

[martinschneider]

When uploading files to AWS we use io.github.martinschneider.justtestlah.utils.JustTestLahFileEntity.JustTestLahFileEntity(File) which allows logging the progress of the upload. This is especially useful for larger files which take a while to send. See io.github.martinschneider.justtestlah.awsdevicefarm.AWSService.upload(File, String, UploadType, Boolean).

The same mechanism should be used for Browserstack, see io.github.martinschneider.justtestlah.configuration.BrowserStackWebDriverBuilder.uploadAppPackage(String). The reason this is not completely obvious to solve is that we use a multipart HttpEntity for Browserstack.