feat: Support for Chat Flow & Agent Support for binding a single chat flow (#765)

Co-authored-by: Yu Yang <72337138+tomasyu985@users.noreply.github.com>
Co-authored-by: zengxiaohui <csu.zengxiaohui@gmail.com>
Co-authored-by: lijunwen.gigoo <lijunwen.gigoo@bytedance.com>
Co-authored-by: lvxinyu.1117 <lvxinyu.1117@bytedance.com>
Co-authored-by: liuyunchao.0510 <liuyunchao.0510@bytedance.com>
Co-authored-by: haozhenfei <37089575+haozhenfei@users.noreply.github.com>
Co-authored-by: July <jiangxujin@bytedance.com>
Co-authored-by: tecvan-fe <fanwenjie.fe@bytedance.com>

idl/app/common_struct/common_struct.thrift

@@ -90,4 +90,27 @@ struct Space {
     2: i64 owner_id,
     3: SpaceStatus status,
     4: string name,
-}
+}
+
+typedef string VariableType
+
+const VariableType VariableTypeKVVariable = 'KVVariable'
+const VariableType VariableTypeListVariable = 'ListVariable'
+
+typedef string VariableChannel
+
+const VariableChannel VariableChannelCustom = 'custom'
+const VariableChannel VariableChannelSystem = 'system'
+const VariableChannel VariableChannelLocation = 'location'
+const VariableChannel VariableChannelFeishu = 'feishu'
+const VariableChannel VariableChannelAPP = 'app'
+
+struct Variable {
+    1: string keyword,
+    2: string default_value,
+    3: VariableType variable_type,
+    4: VariableChannel channel,
+    5: string description,
+    6: bool enable,
+    7: bool prompt_enable,
+}