Make auto-signature help respect popover delay (#46745)

Closes #46191

Release Notes:

- Make the auto signature popover — `"auto_signature_help": true` —
respect `hover_popover_delay`.

crates/editor/src/editor_tests.rs

@@ -48,7 +48,7 @@ use project::{
 };
 use serde_json::{self, json};
 use settings::{
-    AllLanguageSettingsContent, EditorSettingsContent, IndentGuideBackgroundColoring,
+    AllLanguageSettingsContent, DelayMs, EditorSettingsContent, IndentGuideBackgroundColoring,
     IndentGuideColoring, InlayHintSettingsContent, ProjectSettingsContent, SearchSettingsContent,
     SettingsStore,
 };
@@ -13544,6 +13544,7 @@ async fn test_handle_input_for_show_signature_help_auto_signature_help_true(
         cx.update_global::<SettingsStore, _>(|settings, cx| {
             settings.update_user_settings(cx, |settings| {
                 settings.editor.auto_signature_help = Some(true);
+                settings.editor.hover_popover_delay = Some(DelayMs(300));
             });
         });
     });

crates/editor/src/signature_help.rs

@@ -10,6 +10,7 @@ use markdown::{Markdown, MarkdownElement};
 use multi_buffer::{Anchor, MultiBufferOffset, ToOffset};
 use settings::Settings;
 use std::ops::Range;
+use std::time::Duration;
 use text::Rope;
 use theme::ThemeSettings;
 use ui::{
@@ -170,6 +171,10 @@ impl Editor {
             return;
         }
 
+        // If there's an already running signature
+        // help task, this will drop it.
+        self.signature_help_state.task = None;
+
         let position = self.selections.newest_anchor().head();
         let Some((buffer, buffer_position)) =
             self.buffer.read(cx).text_anchor_for_position(position, cx)
@@ -179,14 +184,23 @@ impl Editor {
         let Some(lsp_store) = self.project().map(|p| p.read(cx).lsp_store()) else {
             return;
         };
-        let task = lsp_store.update(cx, |lsp_store, cx| {
+        let lsp_task = lsp_store.update(cx, |lsp_store, cx| {
             lsp_store.signature_help(&buffer, buffer_position, cx)
         });
         let language = self.language_at(position, cx);
 
+        let signature_help_delay_ms = EditorSettings::get_global(cx).hover_popover_delay.0;
+
         self.signature_help_state
             .set_task(cx.spawn_in(window, async move |editor, cx| {
-                let signature_help = task.await;
+                if signature_help_delay_ms > 0 {
+                    cx.background_executor()
+                        .timer(Duration::from_millis(signature_help_delay_ms))
+                        .await;
+                }
+
+                let signature_help = lsp_task.await;
+
                 editor
                     .update(cx, |editor, cx| {
                         let Some(mut signature_help) =