Remove unused class and friend declarations

This forward declaration doesn't match the class defined inside the
function, so the friend declaration does nothing. The friend declaration is
also unneeded, because the function is a member of the class (and so are
types defined within it), so these already have access to private members.

pcbnew/microwave/microwave_tool.h

@@ -28,9 +28,6 @@
 
 #include <tool/tool_menu.h>
 
-// This class is inside MICROWAVE_TOOL::addMicrowaveFootprint
-class MICROWAVE_PLACER;
-
 // Microwave shapes that are created as board modules when the user requests them.
 enum class MICROWAVE_FOOTPRINT_SHAPE
 {
@@ -71,9 +68,6 @@ public:
     void setTransitions() override;
 
 private:
-    // Make the placer class a friend so it can use the create functions
-    friend MICROWAVE_PLACER;
-
     ///> Main interactive tool
     int addMicrowaveFootprint( const TOOL_EVENT& aEvent );