Reduce display_map snapshot creation (#39354)

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

crates/zed/src/zed/quick_action_bar/repl_menu.rs

@@ -54,7 +54,8 @@ impl QuickActionBar {
                     .count()
                     .ne(&0)
                     .then(|| {
-                        let latest = this.selections.newest_display(cx);
+                        let snapshot = this.display_snapshot(cx);
+                        let latest = this.selections.newest_display(&snapshot);
                         !latest.is_empty()
                     })
                     .unwrap_or_default()