Create NN/ANN for sparse vectors

[lusloher]

Feature Request

This ticket is a sub compound of implementing sparse vector functionality to Jina. Currently, there is some low-level code implementation to support sparse vectors. Over the course of this epic we will implement the remaining logic. Main goal is to be able to build a fully neural search system where embedding representations are sparse vectors. This will support certain usecase like TD-IDF, and provide the functionitilty for graph embedding in the future.

Acceptance Criteria

• We should have someway to perform Nearest Neighbours or Approximate Nearest Neighbours search on sparse vectors stored within Jina.

[lusloher]

Link to subfeature: https://jinaai.productboard.com/feature-board/planning/features/7331510