[Keyboard] add Lefty keyboard (#14898)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/lefty/lefty.c

@@ -0,0 +1,43 @@
+/* Copyright 2021 Smoll Chungus (@smollchungus)
+*
+* 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 "lefty.h"
+
+#ifdef OLED_ENABLE
+__attribute__((weak)) void oled_task_user(void) {
+    // Host Keyboard Layer Status
+    oled_write_P(PSTR("Layer: "), false);
+
+    switch (get_highest_layer(layer_state)) {
+        case 0:
+            oled_write_P(PSTR("Default\n"), false);
+            break;
+        case 1:
+            oled_write_P(PSTR("LOWER\n"), false);
+            break;
+        case 2:
+            oled_write_P(PSTR("RAISE\n"), false);
+            break;
+        case 3:
+            oled_write_P(PSTR("SPECIAL\n"), false);
+            break;
+        default:
+            // Or use the write_ln shortcut over adding '\n' to the end of your string
+            oled_write_ln_P(PSTR("Undefined"), false);
+    }
+
+}
+#endif