[FEATURE] Semantic Search should be able to support Exact search

[vamshin]

Is your feature request related to a problem?

In the use cases of semantic search with filtering, its possible to operate on granular tenets. In these cases, Exact Search/Bruteforce would be more efficient to determine results with more accuracy(recall 1.0). Neural plugin should avoid building the graphs and just use plain vectors for Exact Search.

What solution would you like?

Support Exact Search in Neural clause and avoid creating graphs for these use cases.