Epic: Extension image volume - GA launch

[gbartolini]

Extension image volumes are the new method for distributing extensions with CloudNativePG. This epic outlines the tasks necessary to make this feature generally available (GA), with two primary objectives:

• Provide the required extensions that are currently included in the standard container image (see Community repository for PostgreSQL extensions cloudnative-pg#8577).
• Enable external and independent contributions by establishing clear governance and licensing requirements.

Additionally, we plan to:

• Extend the image catalog CRD to accommodate extensions, facilitating progress on [Feature]: dynamic loading of PostgreSQL extensions via image catalogs cloudnative-pg#8495.
• Update the image catalog artifacts for the minimal image to incorporate community-managed extensions.