Feat/dataset service api (#1245)

Co-authored-by: jyong <jyong@dify.ai>
Co-authored-by: StyleZhang <jasonapring2015@outlook.com>

api/fields/installed_app_fields.py

@@ -0,0 +1,25 @@
+from flask_restful import fields
+
+from libs.helper import TimestampField
+
+app_fields = {
+    'id': fields.String,
+    'name': fields.String,
+    'mode': fields.String,
+    'icon': fields.String,
+    'icon_background': fields.String
+}
+
+installed_app_fields = {
+    'id': fields.String,
+    'app': fields.Nested(app_fields),
+    'app_owner_tenant_id': fields.String,
+    'is_pinned': fields.Boolean,
+    'last_used_at': TimestampField,
+    'editable': fields.Boolean,
+    'uninstallable': fields.Boolean,
+}
+
+installed_app_list_fields = {
+    'installed_apps': fields.List(fields.Nested(installed_app_fields))
+}