Compare two graphs

[KasiaS999]

Description

This Pull Request introduces a new feature to compare two graphs with identical structures. The added functionality allows users to analyze differences in performance metrics, such as time or function calls, between two graphs generated from profiling data.

Changes Made

• Implemented the option to compare two graphs in the --compare functionality.
• Ensured that the comparison feature works accurately for graphs with the same structure (pstats and callgrind).

Additional Notes

• Any feedback or suggestions for improvement are welcome.

[codecov]

Codecov Report

Attention: Patch coverage is 18.75000% with 91 lines in your changes are missing coverage. Please review.

Project coverage is 83.71%. Comparing base (14e0d54) to head (5892fcf).

❗ Current head 5892fcf differs from pull request most recent head cf78a30. Consider uploading reports for the commit cf78a30 to get more accurate results

Files	Patch %	Lines
gprof2dot.py	18.75%	91 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #87      +/-   ##
==========================================
- Coverage   86.89%   83.71%   -3.19%     
==========================================
  Files           1        1              
  Lines        2290     2334      +44     
==========================================
- Hits         1990     1954      -36     
- Misses        300      380      +80     

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[jrfonseca]

Otherwise looks ok.

Requiring exact same structure is an annoying limitation -- for example, for sampling profilers, graphs can easily change. But this is a step forward nevertheless. A simple solution to this would be to insert the missing nodes/edges with zero weight to ensure graphs are the same.

[jrfonseca]

Also, we should add some test coverage for this, to ensure this doesn't break.

[KasiaS999]

I added some tests (not sure if satisfying) and resolved tasks from you. When it comes to not requiring exact same structure I will try to tackle this in the near future.

[jrfonseca]

I've rebased this PR, squashed, and merged it as 4d8a733. Thank you