Feat(modules-sdk): Run hooks on application start (#6111)

**What**
- run `onApplicationStart` hook when starting modules

.changeset/neat-seals-help.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/modules-sdk": patch
+---
+
+feat(modules-sdk): run hooks on application start

packages/modules-sdk/src/medusa-app.ts

@@ -308,12 +308,16 @@ export async function MedusaApp(
       }))
   }
 
-  return {
+  try {
-    modules: allModules,
+    return {
-    link: remoteLink,
+      modules: allModules,
-    query,
+      link: remoteLink,
-    entitiesMap: schema.getTypeMap(),
+      query,
-    notFound,
+      entitiesMap: schema.getTypeMap(),
-    runMigrations,
+      notFound,
+      runMigrations,
+    }
+  } finally {
+    await MedusaModule.onApplicationStart()
   }
 }

packages/modules-sdk/src/medusa-module.ts

@@ -1,5 +1,6 @@
 import {
   ExternalModuleDeclaration,
+  IModuleService,
   InternalModuleDeclaration,
   LinkModuleDefinition,
   LoadedModule,
@@ -85,6 +86,21 @@ export class MedusaModule {
       return MedusaModule.getModuleInstance(key)
     })
   }
+  
+  public static onApplicationStart(): void {
+    for (const instances of MedusaModule.instances_.values()) {
+      for (const instance of Object.values(instances) as IModuleService[]) {
+        if (instance?.__hooks) {
+          instance.__hooks?.onApplicationStart
+            ?.bind(instance)()
+            .catch(() => {
+              // The module should handle this and log it
+              return void 0
+            })
+        }
+      }
+    }
+  }
 
   public static clearInstances(): void {
     MedusaModule.instances_.clear()