Use more verbose logging when performing one-time downloading / unpacking of datasets

[ChrisCummins]

🚀 Feature

There are several operations in CompilerGym that can cause expensive downloading / unpacking operations, such as accessing a new dataset, using a new environment, etc. CompilerGym environments should be more verbose in logging when these situations occur as otherwise the user is left wondering why their app has "frozen" on an otherwise benign looking operation like env.reset() of gym.make().