chore: make ignore reason human readable in text output

[gg-mmill]

Context

Following #1024 ,

• small fix to make ignore reasons human readable.
• add ignore reason to json output schema

Validation

Perform scans with ignored secrets (either from config or backend), with the --all-secrets options.

Ensure the output contains ignore info (both for text and json output)

PR check list

• As much as possible, the changes include tests (unit and/or functional)
• If the changes affect the end user (new feature, behavior change, bug fix) then the PR has a changelog entry (see doc/dev/getting-started.md). If the changes do not affect the end user, then the skip-changelog label has been added to the PR.

Note: skipping changelog as it was included in previous MR.

[codecov]

Codecov Report

Attention: Patch coverage is 99.26471% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.09%. Comparing base (6d0d8b8) to head (521885c).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
ggshield/verticals/secret/extended_match.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1031      +/-   ##
==========================================
+ Coverage   92.05%   92.09%   +0.03%     
==========================================
  Files         181      181              
  Lines        7726     7752      +26     
==========================================
+ Hits         7112     7139      +27     
+ Misses        614      613       -1     

Flag	Coverage Δ
unittests	92.09% <99.26%> (+0.03%)	⬆️

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[agateau-gg]

Looks good! Love the stroke "small" word in the PR description 😅.

Thanks for this work. I think the code-base is less confusing thanks to these renamings.