Deny unknown keys in settings in JSON schema so user gets warnings but settings still parses (#30583)

Closes #ISSUE

Release Notes:

- Improved checking of Zed settings so that unrecognized keys show
warnings while editing them

crates/collab_ui/src/panel_settings.rs

@@ -28,6 +28,7 @@ pub struct ChatPanelSettings {
 }
 
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug)]
+#[schemars(deny_unknown_fields)]
 pub struct ChatPanelSettingsContent {
     /// When to show the panel button in the status bar.
     ///
@@ -51,6 +52,7 @@ pub struct NotificationPanelSettings {
 }
 
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug)]
+#[schemars(deny_unknown_fields)]
 pub struct PanelSettingsContent {
     /// Whether to show the panel button in the status bar.
     ///
@@ -67,6 +69,7 @@ pub struct PanelSettingsContent {
 }
 
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug)]
+#[schemars(deny_unknown_fields)]
 pub struct MessageEditorSettings {
     /// Whether to automatically replace emoji shortcodes with emoji characters.
     /// For example: typing `:wave:` gets replaced with `👋`.