Lazy initialization of score and list objects in search.

[isoos]

• Part of Package search index improvements (tracking issue) #8671, with multiple small changes, each verified that improves or does not degrades the performance. Overall improvement seems to be 3-8% depending on the query.
• IndexedScore object is initalized on-demand with the withItemGetter wrapper method. This skips the allocation and more importantly the reset of the score array, and also its population when there is no text search component.
• Early return of query processing when _TextResults.hasNoMatch is set (skips additional post-processing).
• Pre-computed lists can be filtered through either BitArray or IndexedScore index iteration, making it possible to skip the IndexedScore initialization.
• The total hit count calculation is based on the bit array or the indexed score object, there is no need to build a full *Hit list of the result just for counting them.
• Removed nullability in multiple places.
• No functional change otherwise.

[isoos]

Note: I've got mixed results with top-k sorting (vs full result list sorting), not sure why, this needs some further exploration.

Also: now that the overall improvement is verified, I'm happy to split up this PR to incremental parts, if needed.

[sigurdm]

LGTM