feat: Convert Gherkin Script to ship a gherkin/default recipe

Problem/Motivation

Gherkin Script has no way to install its default configuration via Drupal Recipes.

Steps to reproduce

N/A

Proposed resolution

• Match the web* modules: a recipes/default applied from hook_install() only when the module is installed on its own.
• A recipe installs modules with the config installer in syncing mode, which creates simple config but no config entities, so each recipe imports exactly what the module would otherwise create (config.strict: false + config.import). That makes drush recipe equal to drush pm:install, and a second apply a no-op.
• Verified on Drupal 11.4.7 + PHP 8.4 with assertions on: whole-site config identical between the recipe path and the enable path (cucumber_core: 17 of 18 objects, the one difference is a pre-existing views.view.media_library key).
• Everything Gherkin Script ships is a config entity (the gherkin text format and Ace editor, the feature media type, the Gherkin script field and displays), so under a recipe install none of it was created; the recipe imports those seven objects. It also fixes editor.editor.gherkin, whose empty image_upload fails Drupal 11 validation.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ✅ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• N/A