fix: Support JAX array API before and after JAX v0.4.1

[matthewfeickert]

Description

Allow for versions of JAX older and newer than v0.4.1 to work with the same jax_backend code.

• Backport components of:
  • PR feat: Update JAX backend array_type and array_subtype to jax.Array #2079
  • PR test: Loosen tolerance for test_validation[1bin_normsys_mu1] #2085

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Add try-except block to determine what JAX array API is available and use this
  information to set the jax backend array_type and array_subtype.
* Backport components of:
   - PR https://github.com/scikit-hep/pyhf/pull/2079
   - PR https://github.com/scikit-hep/pyhf/pull/2085

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release/v0.7.x@794052f). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

@@                Coverage Diff                @@
##             release/v0.7.x    #2280   +/-   ##
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  Coverage                  ?   98.25%           
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  Files                     ?       69           
  Lines                     ?     4537           
  Branches                  ?      802           
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  Hits                      ?     4458           
  Misses                    ?       47           
  Partials                  ?       32           

Flag	Coverage Δ
contrib	27.55% <0.00%> (?)
doctest	61.07% <0.00%> (?)
unittests-3.10	96.27% <0.00%> (?)
unittests-3.11	96.27% <0.00%> (?)
unittests-3.7	96.25% <0.00%> (?)
unittests-3.8	96.29% <0.00%> (?)
unittests-3.9	96.31% <0.00%> (?)

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