[Keymap] Drashna updates for 0.19 (#19175)

* Fix up bastardkb boards since blackpill support is officially added.
  * Check for blackpill version, not elite c.
  * Add checks in chibiOS config since multiple ARM controllers supported.
  * Rework rules.mk for keymaps to better handle arm vs avr support
* Start moving away from `matrix_*_*` functions.
  * `housekeeping_task_*` instead of `matrix_scan_*`
  * `keyboard_(pre|post)_init_*` instead of `matrix_init_*` 
* Add ℂℴmⅈℂ unicode input method.
* Clean up unicode code to be more compact and flexible.
* Remove/move Pro Micro LED commands to userspace and better filter them
* Fixup OLED code
  * Use newer quantum keycode functions/preprocessors rather than manual bit manipulation
  * Make unicode mode render much more compact/simple.
* Make qmk secrets more self contained
* Remove custom implementation of split watchdog

users/drashna/keyrecords/process_records.h

@@ -45,6 +45,7 @@ enum userspace_custom_keycodes {
     KC_AUSSIE,
     KC_ZALGO,
     KC_SUPER,
+    KC_COMIC,
     KC_ACCEL,
     NEW_SAFE_RANGE // use "NEWPLACEHOLDER for keymap specific codes
 };