WIP: Add fake GPU device generator for scalability testing

[eero-t]

The whole picture and earlier review comments are in the RFC PR https://github.com/intel/intel-device-plugins-for-kubernetes/pull/1104, from which this is split off.

Compared to RFC PR, I've moved / renamed generator code to gpu_fakedev / gpu_fakedev.go and added documentation + intel-gpu-fakedev container for it.

[eero-t]

The 7 plugin tests that remain in "expected" state show:

Error: .github#L1 An unexpected error has occurred and we've been automatically notified. Errors are sometimes temporary, so please try again.

What I should do next?

[eero-t]

While this adds new container for the devices project, program itself does not have any dependencies (outside of Golang standard libraries + golang.org/x/sys/unix).

Currently it does not have unit tests, but I'm not sure what those should do, as this itself is a (scalability) testing tool (for GPU plugin). Most relevant test would be whether GPU plugin reports expected number of GPUs for the content created by the tool, but because it's generating device files, running it requires either root or suitable capability for creating those.

[mythi]

The 7 plugin tests that remain in "expected" state show:

Error: .github#L1 An unexpected error has occurred and we've been automatically notified. Errors are sometimes temporary, so please try again.

What I should do next?

https://www.githubstatus.com/

[eero-t]

Updated doc + rebased on main now that GitHub problems are fixed, so that CI tests run for the first time.

[codecov-commenter]

Codecov Report

Merging #1116 (72f1010) into main (6347609) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 72f1010 differs from pull request most recent head ff5cc41. Consider uploading reports for the commit ff5cc41 to get more accurate results

@@           Coverage Diff           @@
##             main    #1116   +/-   ##
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  Coverage   53.01%   53.01%           
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  Files          40       40           
  Lines        4350     4350           
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  Hits         2306     2306           
  Misses       1917     1917           
  Partials      127      127           

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[eero-t]

@mythi Any comments on this now that release is done?

[eero-t]

Note: fakedev-exporter project relies on this functionality, as documented here: https://github.com/intel/fakedev-exporter/blob/main/deployments/README.md