[Keyboard] Sol keyboard conversion to split common (#5773)

* Split common conversion

* Updated serial and encoder pins

* Fixing default folder until r2

* Fixing oled driver on slave split common

* Fixing keymap compile errors

* Fixing oled inactivity timer on slave split common

* Hoisted oled driver task, init, & activity to keyboard.c

* Update keyboards/sol/config.h

Co-Authored-By: XScorpion2 <rcalt2vt@gmail.com>

* Remove TAPPING_FORCE_HOLD

keyboards/sol/rules.mk

@@ -1,5 +1,3 @@
-SRC += serial.c
-
 # MCU name
 #MCU = at90usb1287
 MCU = atmega32u4
@@ -48,6 +46,9 @@ OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
 # Custom local font file
 OPT_DEFS += -DOLED_FONT_H=\"common/glcdfont.c\"
 
+SPLIT_KEYBOARD = yes
+ENCODER_ENABLE = yes
+
 # Build Options
 #   change to "no" to disable the options, or define them in the Makefile in
 #   the appropriate keymap folder that will get included automatically
@@ -62,6 +63,4 @@ UNICODE_ENABLE = no         # Unicode
 BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
 RGBLIGHT_ENABLE = yes       # Enable WS2812 RGB underlight.  Do not enable this with audio at the same time.
 
-CUSTOM_MATRIX = yes
-
 DEFAULT_FOLDER = sol/rev1