Kernel: Allow the user to specify the virtual console when booting

Author: https://github.com/supercomputer7
Commit: ab52108982
Pull-request: https://github.com/SerenityOS/serenity/pull/6277
Reviewed-by: https://github.com/ElectrodeYT
Reviewed-by: https://github.com/awesomekling

Kernel/CommandLine.h

@@ -72,6 +72,7 @@ public:
     [[nodiscard]] String userspace_init() const;
     [[nodiscard]] Vector<String> userspace_init_args() const;
     [[nodiscard]] String root_device() const;
+    [[nodiscard]] size_t switch_to_tty() const;
 
 private:
     CommandLine(const String&);