Additional Parameters for Structured output

[lmangani]

The current implementation only supports simple TEXT generation. In order to support Structured output and other model features, we need to support additional parameters like the original prompt function, for instance:

model	Model type, either 'gpt-4o-mini' (default), or 'gpt-4o-2024-08-06' (alias: 'gpt-4o')
temperature	Model temperature value between 0 and 1, default: 0.1
struct	Output schema as struct, e.g. {summary: 'VARCHAR', persons: 'VARCHAR[]'}. Will result in STRUCT output.
struct_descr	Descriptions for struct fields that will be added to the model's context, e.g. {summary: 'a 1 sentence summary of the text', persons: 'an array of all persons mentioned in the text'}
json_schema	A json schema that adheres to this guide. Provides more flexibility than the struct/struct_descr parameters. Will result in JSON output.

[lmangani]

Implemented json_schema and custom_prompt see README