feat(apps): add IPostSystemMessageSent event (#35177)

.changeset/happy-nails-fry.md

apps/meteor/app/apps/server/bridges/listeners.js

apps/meteor/app/apps/server/converters/messages.js

apps/meteor/app/lib/server/functions/sendMessage.ts

apps/meteor/server/services/messages/service.ts

apps/meteor/tests/unit/app/apps/server/messages.tests.js

packages/apps-engine/src/definition/messages/IMessage.ts

...-engine/src/definition/messages/IPostSystemMessageSent.ts

packages/apps-engine/src/definition/messages/MessageType.ts

packages/apps-engine/src/definition/messages/index.ts

packages/apps-engine/src/definition/metadata/AppInterface.ts

packages/apps-engine/src/definition/metadata/AppMethod.ts

...ges/apps-engine/src/server/managers/AppListenerManager.ts

packages/apps/src/bridges/IListenerBridge.ts