Containerization

[webbnh]

This PR adds the capability to build and publish the file-relay utility as a container image.

This change provides a Dockerfile which builds a container image that executes the file-relay utility as its entry point. The resulting container can be invoked as though it were the file-relay utility, with file-relay command options specified at the end of the invocation command line.

This change also provides a .dockerignore file and a GitHub Actions workflow which causes the container image to built when a commit is pushed to a release/** branch, when a tag is created or updated, or when a GitHub release is created or updated. On successful build, the container image is exported to Quay.io and tagged with the branch name, Git tag, or release tag, as appropriate.

Note that this PR is based on #10, so the commits from that PR and its precursors will show up here until they are merged.

PBENCH-1258

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (b4784f8) 98.52% compared to head (2d0654d) 98.52%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #7   +/-   ##
=======================================
  Coverage   98.52%   98.52%           
=======================================
  Files           2        2           
  Lines         541      541           
=======================================
  Hits          533      533           
  Misses          8        8           

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[webbnh]

Converting this PR to a draft while I rebase it on #8.

[dbutenhof]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (74ae60d) 98.52% compared to head (848a679) 98.52%.

Additional details and impacted files
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This is really cool... Pbench is feeling envious ...

[webbnh]

This is really cool... Pbench is feeling envious ...

Yeah, but Pbench has way more code and already has a solution (although...well...it could be made better).

Seriously, though, I think I had a reason for not proposing this solution for Pbench, although I don't recall now what it was. 😵

[webbnh]

OK, I think this is now, once again, actually, ready for review (I've left the penultimate commit unchanged and added updates in the commit that follows it for the change in the directory structure from #8, the removal of the PYTHONPATH definition, removal of the package sources now that the installation does the right thing, and some other modest tweaks).