feat(shields): Add splitkb.com Aurora Sofle

* Add new shield for splitkb.com Aurora Sofle, supporting
  keys, encoder(s), displays, and RGB.

Co-authored-by: Cem Aksoylar <caksoylar@users.noreply.github.com>

app/boards/shields/splitkb_aurora_sofle/Kconfig.defconfig

@@ -0,0 +1,53 @@
+# Copyright (c) 2023 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+if SHIELD_SPLITKB_AURORA_SOFLE_LEFT
+
+config ZMK_KEYBOARD_NAME
+    default "Aurora Sofle"
+
+config ZMK_SPLIT_ROLE_CENTRAL
+    default y
+
+endif # SHIELD_SPLITKB_AURORA_SOFLE_LEFT
+
+if SHIELD_SPLITKB_AURORA_SOFLE_LEFT || SHIELD_SPLITKB_AURORA_SOFLE_RIGHT
+
+config ZMK_SPLIT
+    default y
+
+config ZMK_RGB_UNDERGLOW
+    select WS2812_STRIP
+    select SPI
+
+if ZMK_DISPLAY
+
+config SSD1306
+    default y
+
+config I2C
+    default y
+
+config SSD1306_REVERSE_MODE
+    default y
+
+endif # ZMK_DISPLAY
+
+if LVGL
+
+config LV_Z_VDB_SIZE
+    default 64
+
+config LV_DPI_DEF
+    default 148
+
+config LV_Z_BITS_PER_PIXEL
+    default 1
+
+choice LV_COLOR_DEPTH
+    default LV_COLOR_DEPTH_1
+endchoice
+
+endif # LVGL
+
+endif # SHIELD_SPLITKB_AURORA_SOFLE_LEFT || SHIELD_SPLITKB_AURORA_SOFLE_RIGHT