Move print/debug files to quantum (#12069)

* move print/debug files to quantum

* Update comments

quantum/logging/sendchar.c

@@ -0,0 +1,20 @@
+/*
+Copyright 2011 Jun Wako <wakojun@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "sendchar.h"
+
+/* default noop "null" implementation */
+__attribute__((weak)) int8_t sendchar(uint8_t c) { return 0; }