add promxial policy optimization template to pl_examples  (#5394)
add promxial policy optimization template to pl_examples  (#5394)

* add ppo rl lightning template

* flake

* import gym without try as in qnet example

* fix import format

* remove torch.optim import, not required

* fix import format isort

* add trainer argparse

* change name of trajectory collection method

* add repo in references

* fix typo in comments

* use isinstance to verify actionspace type

* use fstring

* deduplication of logic code

* rename unused forloop variable

* use pl.seed_everything instead

* remove unused numpy import

* format string printed on error

* fix typo in comments

Co-authored-by: chaton <5f50a84c1fa3bcff146405017f36aec1a10a9e38@grid.ai>
williamFalcon/pytorch-lightning,williamFalcon/pytorch-lightning