Refactor EInkDisplay (#3299)

* Refactor EInkDisplay
A lot of variant specific code is merged, with the macros pushed to the respective variant.h files.
"Dynamic Partial" code has been purged, pending a rewrite.

* fix: declare class only if USE_EINK, init all members

* refactor: move macros to platformio.ini
Responds to https://github.com/meshtastic/firmware/pull/3299#issuecomment-1966425926

* fix: EInkDisplay::connect() references old macros
Usage was in a block of variant-specific code, which had been intentionally left untouched.

* fix: remove duplicate macros from variant.h

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

variants/m5stack_coreink/platformio.ini

@@ -9,8 +9,9 @@ build_flags =
   ;-D RADIOLIB_VERBOSE
   -Ofast
   -D__MCUXPRESSO
-  -DEPD_HEIGHT=200
-  -DEPD_WIDTH=200
+  -DEINK_DISPLAY_MODEL=GxEPD2_154_M09
+  -DEINK_WIDTH=200
+  -DEINK_HEIGHT=200
   -DUSER_SETUP_LOADED
   -DM5_COREINK 
   -DM5STACK