FT: Plugin Context Data Sharing

In order to allow kn to reuse some (stateful) context that is provided by a plugin, I'm proposing to extend the "plugin contract". The original use case is to share the namespace and name of a function managed by kn-plugin-func that is stored in a local "func.yaml" file. kn must not directly read this file as this would introduce a dependency from kn to kn-func-plugin (in the wrong direction).

The Feature Track Kn Plugin Context Data Sharing will describe the design, this issue is to track the work on this FT.

The current status is "WIP" and "pre Draft" but want to share early.

Start with the linked Feature Track document, “Kn Plugin Context Data Sharing,” and review the proposed extension to the plugin contract. Trace how kn-plugin-func stores function namespace and name in func.yaml and how kn would receive that context without reading the file directly. Done means the design is settled and the plugin and kn implementations share the required state without introducing the dependency described.