Integration rework.

[DomagojGojak]

• The default integration no longer loads automatically; integrations must now be part of the working directory to be loaded.
• The integration config object now includes an entry point for templates (removed hardcoded paths), and component integration options loading has been improved.
• Removed the integration config key and the use_legacy_definitions config key, as they are no longer needed.
• Updated the eject:integration command to make:integration (retained eject:integration as an alias).
• Removed deprecated options from legacy exportable definitions.
• Handoff now automatically determines whether to use legacy definitions based on the working directory setup.
• Moved component design JSON files from pages to the integration folder as view.config.json files.
• Removed the folder containing partially or fully supported integrations that are no longer relevant.
• Enhanced SCSS utility placeholders.
• Removed the Mustache dependency and updated all references to use Handlebars.
• Performed a general config type cleanup.
• Cleaned up ComponentDefinitionOptions to streamline their usage.
• Updated the minimum required version of Axios to 1.7.5.