wasm-shim: Add support for an action (in actionSet) that calls out via ext_proc

[david-martin]

• See https://github.com/Kuadrant/wasm-shim/tree/2c2507b7d3b18eb8a53d5e5c3190c20dd5c3b5a3?tab=readme-ov-file#sample-configuration for more info on the actionSet configuration
• add support for a new 'ai-service'
• it will use the 'ext_proc' protocol https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/ext_proc_filter

[alexsnaps]

This could be done in a "reusable way", so that it may well be used for this too I think. Could be useful/a good idea.

[david-martin]

Suggestion from @maleck13 to implement this first in the wasm-shim before abstracting, then seeing how to make it reusable as a library in proxy-wasm.
Open question about what language the abstraction would be in rust vs c++ vs golang?