Rank search results based on the recency of the match and not the most recent activity on the conversation

Description: Search results are ranked chronologically but based on the last activity time of a conversation containing a match, and not based on the activity time of the search match in the conversation. For example for the search query: acme@acme.com shipment order

1. First result - old match and recent activity: Conversation thread with acme@acme.com with a reply from TODAY but the last mention of "shipment order" was 1 month ago

2. Second result - more recent match but older activity: Conversation thread with acme@acme.com with a reply from YESTERDAY including "shipment order"