[Keyboard] Add Cassini keyboard (#16522)

Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: yiancar <yiancar@gmail.com>

keyboards/protozoa/cassini/rules.mk

@@ -0,0 +1,26 @@
+# MCU name
+MCU = STM32F072
+
+# Bootloader selection
+BOOTLOADER = stm32-dfu
+
+# Wildcard to allow APM32 MCU
+DFU_SUFFIX_ARGS = -v FFFF -p FFFF
+
+# Do not put the microcontroller into power saving mode
+# when we get USB suspend event. We want it to keep updating
+# backlight effects.
+OPT_DEFS += -DCORTEX_ENABLE_WFI_IDLE=TRUE
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes      # Enable Bootmagic Lite
+MOUSEKEY_ENABLE = yes       # Mouse keys
+EXTRAKEY_ENABLE = yes       # Audio control and System control
+CONSOLE_ENABLE = no         # Console for debug
+COMMAND_ENABLE = no         # Commands for debug and configuration
+NKRO_ENABLE = yes           # Enable N-Key Rollover
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
+AUDIO_ENABLE = no           # Audio output