cmStringAlgorithms: Move string functions to the new cmStringAlgorithms.h

This adds the `cmStringAlgorithms.h` header and moves all string functions
from `cmAlgorithms.h` to `cmStringAlgorithms.h`.

Source/cmTargetCompileFeaturesCommand.cxx

@@ -4,9 +4,9 @@
 
 #include <sstream>
 
-#include "cmAlgorithms.h"
 #include "cmMakefile.h"
 #include "cmMessageType.h"
+#include "cmStringAlgorithms.h"
 
 class cmExecutionStatus;
 class cmTarget;