Show rate limit notices (#15515)

This UI change is behind a `ZedPro` feature flag so that it won't be
visible until we're ready to launch that service.

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Marshall <marshall@zed.dev>

crates/assistant/Cargo.toml

@@ -32,7 +32,9 @@ client.workspace = true
 clock.workspace = true
 collections.workspace = true
 command_palette_hooks.workspace = true
+db.workspace = true
 editor.workspace = true
+feature_flags.workspace = true
 fs.workspace = true
 futures.workspace = true
 fuzzy.workspace = true
@@ -53,6 +55,7 @@ ordered-float.workspace = true
 parking_lot.workspace = true
 paths.workspace = true
 project.workspace = true
+proto.workspace = true
 regex.workspace = true
 rope.workspace = true
 schemars.workspace = true
@@ -74,6 +77,7 @@ util.workspace = true
 uuid.workspace = true
 workspace.workspace = true
 picker.workspace = true
+zed_actions.workspace = true
 
 [dev-dependencies]
 ctor.workspace = true