Move rich text escape methods to helper .h .cpp files

src/richtexthelper.cpp

@@ -0,0 +1,18 @@
+#include "richtexthelper.h"
+
+// 3rdparty lib includes
+#include <strutils.h>
+
+namespace espgui {
+
+void richTextEscape(std::string &subject)
+{
+    cpputils::stringReplaceAll('&', "&&", subject);
+}
+
+std::string richTextEscape(std::string_view subject)
+{
+    return cpputils::stringReplaceAll('&', "&&", subject);
+}
+
+} // namespace espgui