[major-change] convert all the stages to subsystem-referenced

This allows to share stages among multiple files

.SimulinkProject/Root.type.Files/simscape_subsystems.type.File.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info />

.SimulinkProject/Root.type.Files/simscape_subsystems.type.File/1.type.DIR_SIGNIFIER.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info />

.SimulinkProject/Root.type.Files/simscape_subsystems_uniaxial.type.File.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info />

.SimulinkProject/Root.type.Files/simscape_subsystems_uniaxial.type.File/1.type.DIR_SIGNIFIER.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info />

.SimulinkProject/Root.type.Files/simscape_subsystems_uniaxial.type.File/nano_hexa_cedrat_1dof.slx.type.File.xml

@@ -0,0 +1,6 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info>
+    <Category UUID="FileClassCategory">
+        <Label UUID="design" />
+    </Category>
+</Info>

.SimulinkProject/Root.type.ProjectPath/7380726a-8c53-4fd9-b49a-eabda89012ae.type.Reference.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info Ref="simscape_subsystems_uniaxial" Type="Relative" />

.SimulinkProject/Root.type.ProjectPath/75279f3d-31b7-450c-80ea-88fc4147a73a.type.Reference.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info Ref="simscape_library" Type="Relative" />

.SimulinkProject/Root.type.ProjectPath/9a090d6d-18eb-46dd-9ba8-558eef0a4238.type.Reference.xml

@@ -0,0 +1,2 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<Info Ref="simscape_subsystems" Type="Relative" />