ep: Increase example capture rate (#57208)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #ISSUE

Release Notes:

- N/A or Added/Fixed/Improved ...

crates/buffer_diff/src/buffer_diff.rs

@@ -267,6 +267,10 @@ impl BufferDiffSnapshot {
             .then(|| self.inner.base_text.text())
     }
 
+    pub fn base_text_exists(&self) -> bool {
+        self.inner.base_text_exists
+    }
+
     pub fn secondary_diff(&self) -> Option<&BufferDiffSnapshot> {
         self.secondary_diff.as_deref()
     }