Replace environment Arc<Mutex> with upstream

[nbigaouette]

In microsoft/onnxruntime#4583 the environment created from the C API is made threadsafe; creating multiple environments from different threads should return the singleton, including the log manager.

The merge commit (f0edd074fb6a957b7c40a5135af61654043ed1c2) is not yet released (1.4.0 is the latest for now).

When a new release is done, using it might simplify the lazy_static used here.