XpressDirect.available(): check there is a valid license

[jsiirola]

Fixes # .

Summary/Motivation:

This updates the Xpress direct (and persistent) interfaces so that available() verified that there is a valid license.

Changes proposed in this PR:

• Add a license check to XpressDirect.available()

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[mrmundt]

So I have feelings about this. Our tests failing tell us if we forgot to renew our licenses, so even though this is correct "in the software engineering" sense, we end up using the failures as an additional way (beyond the solver check job) to ensure that we haven't messed up our solver availability. Happy to be overruled here - it's just a concern.

[jsiirola]

This PR is fixing a bug in pyomo: that is, XpressDirect.available() is returning True when in fact the solver is not available.

The fact that we happened to use this failure to notice that our infrastructure is broken is separate. After this PR is merged, the failing tests will be skipped in the Pyomo tests, but the Jenkins StatusCheck_solvers job will now (correctly) start to fail.

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.

Project coverage is 88.57%. Comparing base (feb8c55) to head (168389d).

Files with missing lines	Patch %	Lines
pyomo/solvers/plugins/solvers/xpress_direct.py	76.92%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3400      +/-   ##
==========================================
+ Coverage   88.52%   88.57%   +0.05%     
==========================================
  Files         883      883              
  Lines      100334   100343       +9     
==========================================
+ Hits        88820    88880      +60     
+ Misses      11514    11463      -51     

Flag	Coverage Δ
linux	86.04% <53.84%> (-0.01%)	⬇️
osx	76.03% <38.46%> (-0.01%)	⬇️
other	86.53% <53.84%> (-0.01%)	⬇️
win	84.38% <38.46%> (-0.01%)	⬇️

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