Fix some semantic index issues (#11216)

* [x] Fixed an issue where embeddings would be assigned incorrectly to
files if a subset of embedding batches failed
* [x] Added a command to debug which paths are present in the semantic
index
* [x] Determine why so many paths are often missing from the semantic
index
* we erroring out if an embedding batch contained multiple texts that
were the same, which can happen if a worktree contains multiple copies
of the same text (e.g. a license).

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>
Co-authored-by: Nathan <nathan@zed.dev>
Co-authored-by: Kyle <kylek@zed.dev>
Co-authored-by: Kyle Kelley <rgbkrk@gmail.com>

crates/assistant2/examples/chat_with_functions.rs

@@ -365,7 +365,7 @@ impl Example {
     ) -> Self {
         Self {
             assistant_panel: cx.new_view(|cx| {
-                AssistantPanel::new(language_registry, tool_registry, user_store, cx)
+                AssistantPanel::new(language_registry, tool_registry, user_store, None, cx)
             }),
         }
     }