Kernel: Make the VirtualConsole index const unsigned instead of unsigned

const:
The index should not be modified in the constructor to avoid unexpected
behavior

Kernel/TTY/VirtualConsole.cpp

@@ -63,7 +63,7 @@ void VirtualConsole::set_graphical(bool graphical)
     m_graphical = graphical;
 }
 
-VirtualConsole::VirtualConsole(unsigned index)
+VirtualConsole::VirtualConsole(const unsigned index)
     : TTY(4, index)
     , m_index(index)
     , m_terminal(*this)

Kernel/TTY/VirtualConsole.h

@@ -38,7 +38,7 @@ class VirtualConsole final : public TTY
     , public VT::TerminalClient {
     AK_MAKE_ETERNAL
 public:
-    VirtualConsole(unsigned index);
+    VirtualConsole(const unsigned index);
     virtual ~VirtualConsole() override;
 
     static void switch_to(unsigned);