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

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

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()