Better handling of tokens near expiry

[ponyisi]

Resolves #473:

• if an auth token is within 60 seconds of expiry, renew it before proceeding with request;
• if a transformation status query returns an auth error, attempt a retry with an updated token;
• add better handling of other error codes when querying transformation status.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84.29%. Comparing base (7e09033) to head (e776afb). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #487 +/- ## ========================================== + Coverage 82.96% 84.29% +1.32% ========================================== Files 26 26 Lines 1403 1515 +112 ========================================== + Hits 1164 1277 +113 + Misses 239 238 -1 ``` | [Flag](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/487/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ssl-hep/ServiceX_frontend/pull/487/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep) | `84.29% <100.00%> (+1.32%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ssl-hep#carryforward-flags-in-the-pull-request-comment) to find out more.

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