Ingests and processes a text, storing its chunks to be used as context.
The context obtained from files is later used in
/chat/completions, /completions, and /chunks APIs.
A Document will be generated with the given text. The Document
ID is returned in the response, together with the
extracted Metadata (which is later used to improve context retrieval). That ID
can be used to filter the context used to create responses in
/chat/completions, /completions, and /chunks APIs.