Rework watcher (#17284)

Heavy Refactoring of the watcher, sorry about this one, I'll keep
iterating on it.

In a nutshell:
- app-dev.ts is maintaining 3 watchers in parallel: manifest, function
and frontComponent

packages/twenty-shared/src/application/applicationManifestType.ts

@@ -1,7 +1,8 @@
 import {
+  PackageJson,
+  type Application,
   type ObjectManifest,
   type ServerlessFunctionManifest,
-  type Application,
 } from '@/application';
 import { type FrontComponentManifest } from '@/application/frontComponentManifestType';
 import { type ObjectExtensionManifest } from '@/application/objectExtensionManifestType';
@@ -16,4 +17,5 @@ export type ApplicationManifest = {
   frontComponents?: FrontComponentManifest[];
   roles?: RoleManifest[];
   sources: Sources;
+  packageJson: PackageJson;
 };