Add player joining

In the platformer scene, whenever you connect a new keyboard or controller, or interact with one already connected, a new player will be created and tied to that input device. Please try to break this system to make sure it works properly.

Assets/Games/Platformer/Platformer Player.prefab

@@ -87,6 +87,7 @@ GameObject:
   serializedVersion: 6
   m_Component:
   - component: {fileID: 627266363752542778}
+  - component: {fileID: 5205514565969078994}
   - component: {fileID: 4323437100190106747}
   - component: {fileID: 9112988359646506999}
   - component: {fileID: 2791557175355662981}
@@ -115,6 +116,36 @@ Transform:
   - {fileID: 317069132541983608}
   m_Father: {fileID: 0}
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!114 &5205514565969078994
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 6546762253351562952}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 62899f850307741f2a39c98a8b639597, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  m_Actions: {fileID: -944628639613478452, guid: 6cbaae0ad99590d468c8b501c0452c36, type: 3}
+  m_NotificationBehavior: 0
+  m_UIInputModule: {fileID: 0}
+  m_DeviceLostEvent:
+    m_PersistentCalls:
+      m_Calls: []
+  m_DeviceRegainedEvent:
+    m_PersistentCalls:
+      m_Calls: []
+  m_ControlsChangedEvent:
+    m_PersistentCalls:
+      m_Calls: []
+  m_ActionEvents: []
+  m_NeverAutoSwitchControlSchemes: 0
+  m_DefaultControlScheme: 
+  m_DefaultActionMap: Player
+  m_SplitScreenIndex: -1
+  m_Camera: {fileID: 0}
 --- !u!212 &4323437100190106747
 SpriteRenderer:
   m_ObjectHideFlags: 0