[Refactoring] Refactor hybrid query code to add explain and rrf in hybrid query context

[vibrantvarun]

Refactor the current code of hybrid query and add explain and rrf details in HybridQueryContext object.

Currently, we have used explicit explain param at multiple places in the code. We need to wrap it under the hybrid query context so that all hybrid query related objects can be transported under the same context and we can avoid feature specific checks.