[Core] Refactor OLED to allow easy addition of other types (#13454)

* add docs

* core changes

* update keyboards to new OLED

* updated users to new OLED

* update layouts to new OLED

* fixup docs

* drashna's suggestion

* fix up docs

* new keyboards with oled

* core split changes

* remaining keyboard files

* Fix The Helix keyboards oled options

* reflect develop

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: mtei <2170248+mtei@users.noreply.github.com>

keyboards/aeboards/ext65/keymaps/default/keymap.c

@@ -62,7 +62,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
   )
 };
 
-#ifdef OLED_DRIVER_ENABLE
+#ifdef OLED_ENABLE
 
 void render_layer_state(void) {
     oled_write_ln(PSTR("LAYER"), false);

keyboards/aeboards/ext65/keymaps/via/keymap.c

@@ -62,7 +62,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
   )
 };
 
-#ifdef OLED_DRIVER_ENABLE
+#ifdef OLED_ENABLE
 
 void render_layer_state(void) {
     oled_write_ln(PSTR("LAYER"), false);

keyboards/aeboards/ext65/keymaps/via/rules.mk

@@ -1 +1,3 @@
 VIA_ENABLE = yes
+OLED_ENABLE = yes
+# OLED_DRIVER = not a real thing