Introduce Tabs to Assistant Panel (#13783)

<img width="1652" alt="image"
src="https://github.com/zed-industries/zed/assets/482957/8397ea87-51aa-4b69-85c7-bf963fe2b08a">

Release Notes:

- N/A

crates/assistant/Cargo.toml

@@ -17,6 +17,7 @@ anthropic = { workspace = true, features = ["schemars"] }
 anyhow.workspace = true
 assistant_slash_command.workspace = true
 async-watch.workspace = true
+breadcrumbs.workspace = true
 cargo_toml.workspace = true
 chrono.workspace = true
 client.workspace = true
@@ -24,7 +25,6 @@ collections.workspace = true
 command_palette_hooks.workspace = true
 editor.workspace = true
 feature_flags.workspace = true
-file_icons.workspace = true
 fs.workspace = true
 futures.workspace = true
 fuzzy.workspace = true