JSON-safe comma splitting for override options (--fact-override, --enc-override)

[isaiahfrantz]

Summary

This PR restores support for comma-separated override lists while preserving JSON values that contain commas (e.g., JSON arrays). It also refactors the parsing logic into a shared helper to avoid duplication across override option classes.

What changed

Override parsing

• --fact-override, --to-fact-override, --from-fact-override now accept:
  • STRING1[,STRING2[,...]]
• Commas are treated as separators only when they are outside of quoted strings and JSON structures ([] / {}), so values like:
  • json_list=(json)["a","b"]
    remain intact.

DRY refactor

• Added shared helper:
  • OctocatalogDiff::Cli::Options.split_override_list in lib/octocatalog-diff/cli/options.rb
• Updated override option implementations to use the helper:
  • lib/octocatalog-diff/cli/options/fact_override.rb
  • lib/octocatalog-diff/cli/options/enc_override.rb

Tests

• Added/updated specs to cover:
  • comma-separated override lists
  • mixed lists with JSON values containing commas
• Specs:
  • spec/octocatalog-diff/tests/cli/options/fact_override_spec.rb
  • spec/octocatalog-diff/tests/cli/options/enc_override_spec.rb

Docs

• Updated facts override docs to describe comma-separated list support + JSON-safe behavior:
  • doc/advanced-override-facts.md
• Updated CLI options reference for fact overrides:
  • doc/optionsref.md

Why

Previously, comma-separated lists were disabled to avoid breaking JSON values (since JSON arrays/objects contain commas). This PR enables both:

• convenience: foo=bar,baz=buzz
• correctness: json_list=(json)["a","b","c"]

Testing

bundle exec rspec \
  spec/octocatalog-diff/tests/cli/options/fact_override_spec.rb \
  spec/octocatalog-diff/tests/cli/options/enc_override_spec.rb

[isaiahfrantz]

@ngrundy can you take a look?