Epic: Switch to structured output/response

Problem/Motivation

Epic to track issues that get us to using structured output/response with all AI providers

Remaining tasks

#3539604: Add support for Gemini PHP client 2.x version that supports tool calling
#3567078: Implement structured response with Gemini module
#3566728: Implement structured response with OpenAI module
#3571105: Research Structured Output in Vertex Provider module
#3577093: Move the schema to be converted to a structured output object