feat(inline-notification): make title/subtitle slottable

Closes #883

docs/src/COMPONENT_API.json

@@ -5218,7 +5218,19 @@
       ],
       "slots": [
         { "name": "__default__", "default": true, "slot_props": "{}" },
-        { "name": "actions", "default": false, "slot_props": "{}" }
+        { "name": "actions", "default": false, "slot_props": "{}" },
+        {
+          "name": "subtitle",
+          "default": false,
+          "fallback": "{subtitle}",
+          "slot_props": "{}"
+        },
+        {
+          "name": "title",
+          "default": false,
+          "fallback": "{title}",
+          "slot_props": "{}"
+        }
       ],
       "events": [
         {

docs/src/pages/components/InlineNotification.svx

@@ -11,6 +11,13 @@ source: Notification/InlineNotification.svelte
 
 <InlineNotification title="Error:" subtitle="An internal server error occurred." />
 
+### Slottable title, subtitle
+
+<InlineNotification>
+  <strong slot="title">Error: </strong>
+  <strong slot="subtitle">An internal server error occurred.</strong>
+</InlineNotification>
+
 ### Hidden close button
 
 <InlineNotification hideCloseButton kind="warning" title="Scheduled maintenance:" subtitle="Maintenance will last 2-4 hours." />