Draft: feat(agents): code-generations for anthropic via agents

What does this merge request do and why?

PoC of using agents for code generations powered by Anthropic model. The MR is build on top of:

• feat(agents): change prompt lookup for agent re... (!1095 - merged)
• feat(agents): code completions for custom model... (!1063 - merged)
• feat(agents): execute code generations via agent (!1096 - merged)