Add origin for ai assist interstitial modal (#24904)

GitOrigin-RevId: 035edf8791b0afdc8c320598d09d99f5e84acc47

services/web/frontend/js/shared/context/types/writefull-instance.ts

@@ -5,6 +5,7 @@ export interface WritefullEvents {
   'writefull-received-suggestions': { numberOfSuggestions: number }
   'writefull-register-as-auto-account': { email: string }
   'writefull-shared-analytics': { eventName: string; segmentation: object }
+  'writefull-ai-assist-show-paywall': { origin?: string }
 }
 
 type InsertPosition = {
@@ -28,6 +29,10 @@ export interface WritefullAPI {
     name: eventName,
     callback: (detail: WritefullEvents[eventName]) => void
   ): void
+  removeEventListener<eventName extends keyof WritefullEvents>(
+    name: eventName,
+    callback: (detail: WritefullEvents[eventName]) => void
+  ): void
   openTableGenerator(): void
   openEquationGenerator(): void
 }