SSE: Add utility methods for HysteresisCommand (#79157)

* add GetCommandsFromPipeline
* refactor method GetCommandType to func GetExpressionCommandType
* add function to create fingerprint frames
* add function to determine whether raw query represents a hysteresis command and a function to patch it with loaded metrics

pkg/expr/graph_test.go

@@ -246,6 +246,41 @@ func TestServicebuildPipeLine(t *testing.T) {
 	}
 }
 
+func TestGetCommandsFromPipeline(t *testing.T) {
+	pipeline := DataPipeline{
+		&MLNode{},
+		&DSNode{},
+		&CMDNode{
+			baseNode: baseNode{},
+			CMDType:  0,
+			Command:  &ReduceCommand{},
+		},
+		&CMDNode{
+			baseNode: baseNode{},
+			CMDType:  0,
+			Command:  &ReduceCommand{},
+		},
+		&CMDNode{
+			baseNode: baseNode{},
+			CMDType:  0,
+			Command:  &HysteresisCommand{},
+		},
+	}
+	t.Run("should find command that exists", func(t *testing.T) {
+		cmds := GetCommandsFromPipeline[*HysteresisCommand](pipeline)
+		require.Len(t, cmds, 1)
+		require.Equal(t, pipeline[4].(*CMDNode).Command, cmds[0])
+	})
+	t.Run("should find all commands that exist", func(t *testing.T) {
+		cmds := GetCommandsFromPipeline[*ReduceCommand](pipeline)
+		require.Len(t, cmds, 2)
+	})
+	t.Run("should not find all command that does not exist", func(t *testing.T) {
+		cmds := GetCommandsFromPipeline[*MathCommand](pipeline)
+		require.Len(t, cmds, 0)
+	})
+}
+
 func getRefIDOrder(nodes []Node) []string {
 	ids := make([]string, 0, len(nodes))
 	for _, n := range nodes {