Add test coverage to linux/osx GitHub actions

[mrmundt]

Fixes N/A

Summary/Motivation:

The introduction of coverage reports into Github Actions get us one step closer to removing other external dependencies.

Changes proposed in this PR:

• Add coverage report uploads to Unix workflow

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]

The Appveyor build is giving this message:

Cannot assign job to clouds/groups 'pro, pro-backup'. All clouds within the group are either failing, offline, busy or reached build minutes quota.

The failure isn't related to the PR.

[codecov]

Codecov Report

Merging #1359 into master will increase coverage by 0.16%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1359      +/-   ##
==========================================
+ Coverage   71.37%   71.53%   +0.16%     
==========================================
  Files         542      542              
  Lines       83764    84309     +545     
==========================================
+ Hits        59783    60311     +528     
- Misses      23981    23998      +17     

Impacted Files	Coverage Δ
pyomo/solvers/plugins/solvers/GAMS.py	77.92% <0.00%> (+0.59%)	⬆️
pyomo/solvers/plugins/solvers/IPOPT.py	93.57% <0.00%> (+2.75%)	⬆️
pyomo/core/base/block.py	89.74% <0.00%> (+3.17%)	⬆️
pyomo/contrib/pynumero/extensions/utils.py	74.07% <0.00%> (+3.70%)	⬆️
pyomo/scripting/pyomo_parser.py	75.40% <0.00%> (+5.40%)	⬆️

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[jsiirola]

@mrmundt: we are seeing problems uploading to codecov now:

ERROR: The coverage upload was rejected because the workflow run is either not in-progress or finished a while ago. Please make sure the workflow run is in-progress and is not stale for uploads to process correctly.

[mrmundt]

@mrmundt: we are seeing problems uploading to codecov now:

ERROR: The coverage upload was rejected because the workflow run is either not in-progress or finished a while ago. Please make sure the workflow run is in-progress and is not stale for uploads to process correctly.

And it's failing for OSX now. Sigh. Lovely. I'll see what's up.

[jsiirola]

@mrmundt, @blnicho: I think I am done playing with this. linux/osx are now working and pushing coverage to codecov. I snuck in a few other changes (mostly renaming things to match the new Travis names). If you agree, then I think we can merge!

[mrmundt]

Looks good to me! Thanks for fiddling with it.