Extract an `ExcerptRange` containing a `context` field in `multi_buffer`

This lays the groundwork for adding an optional `primary` field that can
be supplied to provide the "jump to" feature.
ffb75b0f02Antonio Scandurra committed on 6/8/2022, 10:13:04 AMparentd56cc1a
6 files changedLine totals unavailable