Rust native atari environments

[taku-y]

Implements an environment that wraps atari-env. It does not require python interpreter to run.

• Add an example of running a random policy on the environment.
• Add the path to the ROM directory in the configuration of the environment
• Add mapping from the name of each game and ROM file names
• Test training on Pong with DQN
• Add the random no-op steps when resetting
• Add explanation for building atari-sys on MacOS