Specify interface requirements as an C++ concept

PR #19440.

src/base/path.cpp

@@ -39,6 +39,7 @@
 #include <QRegularExpression>
 #include <QStringView>
 
+#include "base/concepts/stringable.h"
 #include "base/global.h"
 
 #if defined(Q_OS_WIN)
@@ -69,6 +70,9 @@ namespace
 #endif
 }
 
+// `Path` should satisfy `Stringable` concept in order to be stored in settings as string
+static_assert(Stringable<Path>);
+
 Path::Path(const QString &pathStr)
     : m_pathStr {cleanPath(pathStr)}
 {