Support s3 log dirs in TensorboardLogger

[hengoren]

What does this PR do?

• Parse and identify S3 paths when creating TensorboardLogger
  • This prevents them from being modified when being passed to Path and allows tensorboard to properly log to s3
• Return a string instead of a PosixPath object to hopefully future-proof against any internal tensorboard changes (happy to revert this)

What issue(s) does this change relate to?

Fixes #3892

Before submitting

• Have you read the contributor guidelines?
• Is this change a documentation change or typo fix? If so, skip the rest of this checklist.
• Was this change discussed/approved in a GitHub issue first? It is much more likely to be merged if so.
• Did you update any related docs and document your change?
• Did you update any related tests and add any new tests related to your change? (see testing)
• Did you run the tests locally to make sure they pass?
  • a fresh clone of main and running make test as outlined in CONTRIBUTING.md led to 28 failures
  • The tests I added pass
• Did you run pre-commit on your change? (see the pre-commit section of prerequisites)
  • Similarly, there are several pyright errors on main. Mostly related to huggingface models, but also a few hits in the MLFlow object store and the optimizer monitor tests.

Happy to get to the bottom of the tests and pre-commit hooks, but figured it'd be easier to open the PR first