FEATURE: Enhance AI debugging capabilities and improve interface adjustments (#577)

* FIX: various RAG edge cases

- Nicer text to describe RAG, avoids the word RAG
- Do not attempt to save persona when removing uploads and it is not created
- Remove old code that avoided touching rag params on create

* FIX: Missing pause button for persona users

* Feature: allow specific users to debug ai request / response chains

This can help users easily tune RAG and figure out what is going
on with requests.

* discourse helper so it does not explode

* fix test

* simplify implementation

test/javascripts/unit/models/ai-persona-test.js

@@ -87,6 +87,9 @@ module("Discourse AI | Unit | Model | ai-persona", function () {
       vision_enabled: true,
       vision_max_pixels: 100,
       rag_uploads: [],
+      rag_chunk_tokens: 374,
+      rag_chunk_overlap_tokens: 10,
+      rag_conversation_chunks: 10,
     };
 
     const aiPersona = AiPersona.create({ ...properties });