Change Details

This diff introduces utilities for storing and using calculated SearchIndex for each thread in `threadStore`. Depends on D8899.

Solution for [ENG-4552](https://linear.app/comm/issue/ENG-4552/create-searchindex-selector). This diff introduces utilities for storing and using calculated SearchIndex for each thread in `threadStore`. Depends on D8899.

Solution for [ENG-4552](https://linear.app/comm/issue/ENG-4552/create-searchindex-selector). This diff introduces utilities for storing and using calculated SearchIndex for each thread in `threadStore`. Depends on D8899.