- Add ShellVariablesPreferences struct with KeySeparator field (default: '_')
- Update shellVariablesEncoder to use configurable separator
- Add --shell-key-separator CLI flag
- Add comprehensive tests for custom separator functionality
- Update documentation with example usage for custom separator
This feature allows users to specify a custom separator (e.g. '__') when
outputting shell variables, which helps disambiguate nested keys from
keys that contain underscores in their names.
Example:
yq -o=shell --shell-key-separator='__' file.yaml
Fixes ambiguity when original YAML keys contain underscores.
