Change auth strategy to using find_or_create_token endpoint

[fwfichtner]

Like discussed in in #484 this simplifies authentication by using the find_or_create_token-endpoint and removing all other auth-endpoints. If all is good users should not notice this change besides when their tokens expire, then they should now just be re-created (I couldn't test that because I had no expired tokens available for testing that).

auth.refresh_token() has been deprecated.

Closes #484
Fixes #764

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📚 Documentation preview 📚: https://earthaccess--782.org.readthedocs.build/en/782/

[fwfichtner]

Oh, didn't have those errors locally and will check what went wrong there. Edit: I only ran the integration tests -.-

[fwfichtner]

I am not sure about this and could just initialize with an empty dict to make mypy happy. The rest also failed on main for me I think.

[chuckwondo]

@fwfichtner, you can safely ignore the failing integration tests. They are all tests that will pass once the PR is merged. We still don't know why this is happening, but we've seen it a few recent PRs.

Regarding the failing unit tests, I'll comment in the code.

[chuckwondo]

@fwfichtner, looks good! Thank you!

[chuckwondo]

@mfisher87 and/or @betolink, either of you care to take a quick look at this PR before I merge it?

[mfisher87]

I'm not going to be able to take a close look at this in the short term. Funding & time-management struggles 😩

[fwfichtner]

Thanks for the review @chuckwondo

[mfisher87]

@chuckwondo thanks for merging! fyi I just got my funding confirmed yesterday; it's not much, but I'm out of "am I funded for this at all?" space now :)