[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/rgbkb/zen/rev2/keymaps/default/keymap.c

@@ -103,7 +103,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
 }
 
 
-#if OLED_DRIVER_ENABLE
+#if OLED_ENABLE
 const char* layer_name_user(uint32_t layer) {
   switch (layer) {
     case _QWERTY:

keyboards/rgbkb/zen/rev2/rev2.c

@@ -1,6 +1,6 @@
 #include "rev2.h"
 
-#ifdef OLED_DRIVER_ENABLE
+#ifdef OLED_ENABLE
 #include "split_util.h"
 #include "oled_driver.h"
 

keyboards/rgbkb/zen/rev2/rules.mk

@@ -1,9 +1,9 @@
 ENCODER_ENABLE = yes
 
-OLED_DRIVER_ENABLE = no
+OLED_ENABLE = no
 
 # Setup so that OLED can be turned on/off easily
-ifeq ($(strip $(OLED_DRIVER_ENABLE)), yes)
+ifeq ($(strip $(OLED_ENABLE)), yes)
   # Custom local font file
   OPT_DEFS += -DOLED_FONT_H=\"common/glcdfont.c\"
 endif