[WIP] Replace meta_tags.csv with hparams.yaml

[S-aiueo32]

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?

Fixes #1212.

[pep8speaks]

Hello @S-aiueo32! Thanks for opening this PR.

• In the file playground/model.py:

Line 70:69: W292 no newline at end of file

• In the file pytorch_lightning/core/saving.py:

Line 60:8: E111 indentation is not a multiple of four

• In the file pytorch_lightning/trainer/training_io.py:

Line 340:111: E501 line too long (115 > 110 characters)

Do see the Hitchhiker's guide to code style

[S-aiueo32]

Oh, I have a lot of mistakes with git. I close once.