Expose ingest and query parameters via api with default values

[simjak]

Expose configurable parameters: Ingest:

• [x] - chunk_size
• [x] - chunk_strategy
• [x] - encoder (already done)

Query:

• [ ] - query transformation options (query fusion, step-back, query rewrite)
• [ ] - top_k
• [ ] - top_n and relevancy score

Maybe some more, depending on testing/evaluation methods