Re-applies https://github.com/zed-industries/zed/pull/30840
This PR re-applies the initial
[PR](https://github.com/zed-industries/zed/pull/30840). As it was closed
because it was hard to land, because of the many conflicts. This PR
re-applies the changes for it.
In several cases we were creating multiple display_map
snapshots within the same root-level function call.
Creating a display_map snapshot is quite slow, and in some
cases we were creating the snapshot multiple times.
Release Notes:
- N/A