[Keyboard] Support for dumbpad_v3x (#18663)

* feat: support for dumbpad_v3x

- all credit goes to
- ref: https://github.com/qmk/qmk_firmware/pull/16285

- included comment from noroadsleft
- ref: https://github.com/qmk/qmk_firmware/pull/16285#pullrequestreview-1038213899

* fix: add newline on every .c, .h, .mk files end

* feat: response to change https://github.com/qmk/qmk_firmware/pull/18663#discussion_r991515821

* feat: response to change https://github.com/qmk/qmk_firmware/pull/18663#discussion_r991516192

keyboards/dumbpad/v3x/rules.mk

@@ -0,0 +1,23 @@
+# MCU name
+MCU = atmega32u4
+
+# Bootloader selection
+BOOTLOADER = caterina
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes      # Enable Bootmagic Lite
+MOUSEKEY_ENABLE = no       # 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 = no           # Enable N-Key Rollover
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
+AUDIO_ENABLE = no           # Audio output
+
+ENCODER_ENABLE = yes
+
+RGB_MATRIX_ENABLE = yes
+RGB_MATRIX_DRIVER = WS2812