Remove unused imports

[ksbeattie]

Fixes/Addresses:

The next step in #1162: this PR removes all unused imports as reported by pylint and adds that check to GHA.

Summary/Motivation:

Clean the code up a little bit.

Changes proposed in this PR:

• Quite a few files changed, this will require some thorough testing to make sure it hasn't broken anything.

Legal Acknowledgement

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1. I agree my contributions are submitted under the copyright and license terms described in the LICENSE.md file at the top level of this directory.
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.

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes missing coverage. Please review.

Project coverage is 38.47%. Comparing base (aad29e3) to head (e0ce1c6).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
foqus_lib/gui/sinter/sinter_config.py	0.00%	1 Missing ⚠️
foqus_lib/gui/uq/dialogTest.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1251      +/-   ##
==========================================
- Coverage   38.87%   38.47%   -0.40%     
==========================================
  Files         165      164       -1     
  Lines       37281    37020     -261     
  Branches     5728     5728              
==========================================
- Hits        14492    14243     -249     
+ Misses      21662    21650      -12     
  Partials     1127     1127              

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[boverhof]

Looks good