Support of artifacts subfolders

Right now Bitrise doesn’t support subfolders in artifacts folder. All files from subfolders are just ignored.
We need support for at least 1 level subfolders.

Our case:
We use FBSnapshotTestCase library for app snapshot testing. When some tests fail then this library creates a bunch of images to help developers to figure out what’s wrong. Image are grouped by test case classes. Groups are represented by folders, that means subfolders in artifacts folder. So we don’t see artifacts that we need.

Why do we need it:

  1. We want to be able viewing artifact images in web browser.
  2. We want to have images grouping.
  3. Other CI systems that we used before had this feature.

Thank you for the feature request! :upside_down_face: