Options propagation

[jean-michelet]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the issue has not already been raised

Issue

By default, the generated templates pass options to the autoloader, which are then propagated to all loaded plugins.
This behavior can cause errors with external plugins if they receive unexpected properties or values in options

Here’s an example of the issue in the demo repository:
fastify/demo#119

Should we continue to do this?
Or simply add doc to prevent this kind of errors in the future?