patch_name method for dir spools

[ahmadtourei]

Description

This PR adds a method named patch_name() that returns the name of a patch in a directory spool.
It is related to discussion #460.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes.
• documented the new feature with docstrings or appropriate doc page.
• included a test. See testing guidelines.
• your name has been added to the contributors page (docs/contributors.md).
• added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.85%. Comparing base (ad2ecb5) to head (89b94e8).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #461   +/-   ##
=======================================
  Coverage   99.85%   99.85%           
=======================================
  Files         115      115           
  Lines        9372     9387   +15     
=======================================
+ Hits         9358     9373   +15     
  Misses         14       14           

Flag	Coverage Δ
unittests	99.85% <100.00%> (+<0.01%)	⬆️

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[ahmadtourei]

I wonder how I can get patch's name from memory spools so we can have another patch_name() method for memory spools. Please let me know your thoughts @d-chambers.

[d-chambers]

Ok, let's look at this a bit more next week. This week is rather busy with the holiday and the tutorial Monday.

[d-chambers]

superseded by #471.