Fix excluded file creation (#12620)

Fixes https://github.com/zed-industries/zed/issues/10890

* removes `unwrap()` that caused panics for text elements with no text,
remaining after edit state is cleared but project entries are not
updated, having the fake, "new entry"
* improves discoverability of the FS errors during file/directory
creation: now those are shown as workspace notifications
* stops printing anyhow backtraces in workspace notifications, printing
the more readable chain of contexts instead
* better indicates when new entries are created as excluded ones


Release Notes:

- Improve excluded entry creation workflow in the project panel
([10890](https://github.com/zed-industries/zed/issues/10890))

crates/project/src/project_tests.rs

@@ -3127,6 +3127,7 @@ async fn test_buffer_identity_across_renames(cx: &mut gpui::TestAppContext) {
         })
         .unwrap()
         .await
+        .to_included()
         .unwrap();
     cx.executor().run_until_parked();
 
@@ -4465,6 +4466,7 @@ async fn test_create_entry(cx: &mut gpui::TestAppContext) {
         })
         .unwrap()
         .await
+        .to_included()
         .unwrap();
 
     // Can't create paths outside the project