feat(wandb): save models on wandb

[borisdayma]

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?
• If you made a notable change (that affects users), did you update the CHANGELOG?

What does this PR do?

This PR allows to save checkpoints in wandb directory which is uploaded at the end of the script. See example

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Merging #1339 into master will decrease coverage by 0%.
The diff coverage is 67%.

@@          Coverage Diff           @@
##           master   #1339   +/-   ##
======================================
- Coverage      92%     92%   -0%     
======================================
  Files          62      62           
  Lines        3239    3242    +3     
======================================
+ Hits         2966    2968    +2     
- Misses        273     274    +1     

[williamFalcon]

awesome!