refactor: Update 'core' app references to 'admin'

ui/admin/package.json

@@ -1,8 +1,8 @@
 {
-  "name": "core",
+  "name": "admin",
   "version": "0.0.0",
   "private": true,
-  "description": "Core UI for Boundary.",
+  "description": "Admin UI for Boundary.",
   "license": "MPL-2.0",
   "author": "HashiCorp",
   "directories": {