Create create_env.py

[mhdmyz]

I highly suggest for simplifying and easier debugging and better readability and understandability of the codes, the environment creation gets it's own function and gets separated from the train and test functions. One of the prominent advantages of FinRL-Meta is it's modularity and having different independent layers, which the proposed change helps going further in this direction.

[zhumingpassional]

Thanks for your codes.

in the function create_test_env, should we consider stockEnv?

[mhdmyz]

I didn't understand your question. Consider stockEnv for what?

[zhumingpassional]

if users want to use stockEnv to train their agent, the code does not support, yes?

[mhdmyz]

Got you! Yeah, the create_env.py only corresponds to the CryptoEnv. It can be easily generalized to other environments as well later. Therefore maybe for now it's better to rename and replace it in the env_crypto_trading folder. Thanks for your exquisite remark!

[zhumingpassional]

Now that create_crypto_env.py is created, should this PR be ignored?