cmCommand: deprecate functions GetMakefile and SetError

Replace the members for the Makefile and the Error with a
cmExecutionStatus.  Re-implement GetMakefile and SetError based on that.

Both functions should be called directly on the cmExecutionStatus that is
passed to InitialPass.  This will help us make all Commands immutable and
remove the need for cloning.

Source/cmExecutionStatus.h

@@ -3,6 +3,11 @@
 #ifndef cmExecutionStatus_h
 #define cmExecutionStatus_h
 
+#include <cmConfigure.h> // IWYU pragma: keep
+#include <string>
+
+class cmMakefile;
+
 /** \class cmExecutionStatus
  * \brief Superclass for all command status classes
  *
@@ -11,14 +16,26 @@
 class cmExecutionStatus
 {
 public:
+  cmExecutionStatus(cmMakefile& makefile)
+    : Makefile(makefile)
+    , Error("unknown error.")
+  {
+  }
+
   void Clear()
   {
+    this->Error = "unknown error.";
     this->ReturnInvoked = false;
     this->BreakInvoked = false;
     this->ContinueInvoked = false;
     this->NestedError = false;
   }
 
+  cmMakefile& GetMakefile() { return this->Makefile; }
+
+  void SetError(std::string const& e) { this->Error = e; }
+  std::string const& GetError() const { return this->Error; }
+
   void SetReturnInvoked() { this->ReturnInvoked = true; }
   bool GetReturnInvoked() const { return this->ReturnInvoked; }
 
@@ -32,6 +49,8 @@ public:
   bool GetNestedError() const { return this->NestedError; }
 
 private:
+  cmMakefile& Makefile;
+  std::string Error;
   bool ReturnInvoked = false;
   bool BreakInvoked = false;
   bool ContinueInvoked = false;