[Features] postgresql support AGE extension

[earayu]

I am currently developing a RAG (Retrieval-Augmented Generation) application called ApeRAG. As part of this project, I need to use PostgreSQL as a graph database to manage and query complex relationships within the data. The Apache AGE (A Graph Extension) is a perfect fit for this requirement, as it provides powerful graph database capabilities directly within PostgreSQL.

However, the current PostgreSQL addon provided by KubeBlocks does not seem to include the AGE extension in its Docker image, and there is no configuration option to enable it.

Describe the solution you'd like

I would like to request official support for the Apache AGE extension in the KubeBlocks PostgreSQL addon. This would ideally involve:

1. Including AGE in the base image: Building the age extension from source and including the necessary binaries in the apecloud/spilo Docker image used by the addon.
2. Making it configurable: Adding an option (e.g., in the values.yaml or through a component parameter) to enable the age extension. When enabled, it should be added to the shared_preload_libraries in the postgresql.conf file.

This would allow users to easily deploy a graph-capable PostgreSQL instance with KubeBlocks, which is essential for modern applications dealing with complex, interconnected data, such as RAG, social networks, and fraud detection systems.

Why is this feature important?

Adding support for Apache AGE would significantly enhance the capabilities of the KubeBlocks PostgreSQL addon, transforming it from a purely relational database into a powerful multi-model database. This would attract more users who require graph database features without the overhead of managing a separate graph database system.

Thank you for considering this feature request.