add Singularity support for "dockerFile"

[misterbrandonwalker]

Add ability to use dockerFile with singularity.

1. Convert dockerFile into singularity recipe via sypthon.
2. Then use singularity build to build image

[mr-c]

Thank you @misterbrandonwalker !

Can you add a test?

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (e4b5d92) 83.77% compared to head (b8338ca) 83.58%.

Files	Patch %	Lines
cwltool/singularity.py	90.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1938      +/-   ##
==========================================
- Coverage   83.77%   83.58%   -0.19%     
==========================================
  Files          46       46              
  Lines        8201     8217      +16     
  Branches     2178     2146      -32     
==========================================
- Hits         6870     6868       -2     
- Misses        855      863       +8     
- Partials      476      486      +10     

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[mr-c]

@misterbrandonwalker Does make test pass for you? Alternatively, tox -e py311-unit (replacing 311 with whatever Python version you have)

[misterbrandonwalker]

The test passes for me with tox I think the issue now is with how I am using current working directory rather than /tmp I see permissions error on the runner
https://github.com/common-workflow-language/cwltool/actions/runs/6932721232/job/18861573891#step:8:1696

However I added to comment here if I try to use /tmp to execute singularity it will crash
main...misterbrandonwalker:cwltool:singularityFile#diff-2cbd89e23f6e4c3f1f7df787bc1ebf9f32408c48b13125b70c6c31111a119b1aR173

FATAL: Unable to create build: 'noexec' mount option set on /tmp, temporary root filesystem

[mr-c]

Thank you @misterbrandonwalker !