* add adr suggesting a new design to support a multi-source architecture for agent skills
* add deciders
* move the adr to the decisions folder
* remove unnecessary section
* describe adding a custom skill source
* update
* address comments
* add constructor overloads to inline skill resource and script
* consider ai-function as an alternative for skill script and skill resource model classes
* update decision outcome section and sync adr with latest changes in the code
SergeyMenshykh