Move all tests to gym/tests/...

[RedTachyon]

See Issue #2424

This is kinda WIP, we have to make sure that all the tests actually trigger and pass.

Also from a quick local test it seems that some of the tests have internal imports. PyCharm did its best to convert them, but it might need some more attention.

[jkterry1]

@RedTachyon this tentatively looks good to me, however the first 4 file renames shown in the files changed tab don't make a lot of sense to me?

[RedTachyon]

@jkterry1 Do you mean gym/envs/tests/__init__.py → gym/tests/__init__.py etc?

It's marked as renames, but my guess is that it's the diff failing to understand moved files. There was a bunch of inits in the previous version under gym/envs/tests, gym/wrappers/tests, and now there's a bunch of inits under gym/tests/envs, gym/tests/wrappers and so on. So it tried to map the former to the latter, but it got a bit wonky in the process because in the end it's just all empty __init__s

[jkterry1]

I mean things like "gym/spaces/tests/init.py → gym/tests/envs/init.py"

[jkterry1]

Oh, no that should be a bad diff. You're right.