Added the diff command - for enabling forensic analysis of checkpoint differences in Kubernetes

[Lorygold]

Introduces a diff command to compare container checkpoints and highlight changes in tasks and runtime state. Supports tree and JSON views, helping security engineers investigate incidents by comparing two checkpoints, making changes more visible and easier to analyze.

Resolves #173

[github-actions]

Test Results

73 tests  +12   73 ✅ +12   3s ⏱️ -1s
 1 suites ± 0    0 💤 ± 0 
 1 files   ± 0    0 ❌ ± 0 

Results for commit 4c56c27. ± Comparison against base commit d4ddee6.

♻️ This comment has been updated with latest results.

[adrianreber]

Did you forget to commit some changes? You reference the function DiffTasks() is not defined anywhere from what I can see.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 68.90080% with 116 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.41%. Comparing base (d4ddee6) to head (4c56c27).

Files with missing lines	Patch %	Lines
cmd/diff.go	67.64%	72 Missing and 27 partials ⚠️
internal/diff_types.go	74.24%	15 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #192      +/-   ##
==========================================
- Coverage   76.00%   74.41%   -1.60%     
==========================================
  Files          13       15       +2     
  Lines        1288     1661     +373     
==========================================
+ Hits          979     1236     +257     
- Misses        232      319      +87     
- Partials       77      106      +29     

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[adrianreber]

The current error is because the test will try to compile each commit. The best thing to do here, because it is all connected, just squash the commits.

[adrianreber]

Looks good so far. Please add tests. The goal is to have pretty good code coverage with our tests.

You could also add the diff feature to the README.md file.

[github-actions]

Library Size Check Failed

The library size increase exceeds the allowed threshold.

Size Check Output

[Lorygold]

Hello everybody, I've added bats tests and the diff command to the readme file

Let me know!

[adrianreber]

The library size CI check failure is not a problem. This should go away if you do a rebase (git pull --rebase and then another force push should solve this).

From my point of view this is almost ready. Some smaller changes would be nice:

• please add unit tests for this file internal/diff_types.go
• the formatting does not always look correct

┌─ Memory Changes ─────────────────────────────────────────────┐
│ = No change
└───────────────────────────────────────────────────────────────┘
┌─ Process Changes ────────────────────────────────────────────┐
└───────────────────────────────────────────────────────────────┘

The upper border seems to be on character shorter than the lower border.

• Please rewrite the commit message. I see you squashed all your commits, thanks, but now we need one nicely formatted commit message. Also see https://github.com/checkpoint-restore/checkpointctl?tab=contributing-ov-file
• Have a subject line of 50 characters in your commit message and a description of your changes which wraps at 72 characters.

With these changes I think we could merge this is a first step and then if necessary adapt it to future needs.