Use IndexedScores in package and SDK doc page search + fixing weight.

[isoos]

• Last part of the split in Reduce the memory allocation during search with mutable IndexedScore. #8225.
• documentation searches use the searchWords method, and by applying the reuse of the internal IndexedScore, we spare Map building for multi-word searches
• Also fixes the weight handling: previously it was applied on each word, making the score of such queries really low. Instead, we should either reset it to 1.0 (as in Reduce the memory allocation during search with mutable IndexedScore. #8225), or use a power-exponent adjustment (as in the separate commit). I think the adjustment here is better for the understanding.
• _scoreDocs is no longer used
• searchWords's limitToIds parameter is no longer used