Search: Include Additional Items in the Index

Some plugins, like BuddyPress, include items that aren't currently included in Jetpack's search index. **Can we update the index to include BuddyPress-related items like groups or user profile information?**

If possible, can we configure it to pick up plugin-specific items like this so that these things are included for other plugins as well?

internal ref: 1272364-zen

The issue does not name files, tests, or an entry point; begin by locating Jetpack's search indexing path and how BuddyPress groups and profile information are represented. Done would require BuddyPress-related items to appear in the index and a confirmed approach for supporting comparable plugin-specific items.

Written by the indexing model from the issue text.