[New Shield] Murphpad (#806)

* initial commit

* initial commit

* Encode, OLED, and RGB Nice Nano support added as well as refining default keymap.

* tweaking keymap

* Prepared murphpad for PR. Includes adding support for second encoder, OLED, and underglow RGB

* Enabled OLED by default.

* removed naked60 config files

* Per PR feedback from ZMK maintainers, added hardware metadata file and renamed Pro Micro pins.

* removed tabs from keymap and replaced with normal spaces

* Update app/boards/shields/murphpad/murphpad.keymap

Co-authored-by: Nick Winans <nick@winans.codes>

* Update app/boards/shields/murphpad/murphpad.zmk.yml

Co-authored-by: Nick Winans <nick@winans.codes>

* Update app/boards/shields/murphpad/murphpad.zmk.yml

Co-authored-by: Nick Winans <nick@winans.codes>

Co-authored-by: honorless <86894501+lesshonor@users.noreply.github.com>
Co-authored-by: Nick Winans <nick@winans.codes>

app/boards/shields/murphpad/boards/nice_nano.conf

@@ -0,0 +1,3 @@
+# Uncomment both to enable underglow
+CONFIG_ZMK_RGB_UNDERGLOW=y
+CONFIG_WS2812_STRIP=y

app/boards/shields/murphpad/boards/nice_nano.overlay

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2021 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+&spi1 {
+	compatible = "nordic,nrf-spim";
+	status = "okay";
+	mosi-pin = <31>;
+	// Unused pins, needed for SPI definition, but not used by the ws2812 driver itself.
+	sck-pin = <5>;
+	miso-pin = <7>;
+
+	led_strip: ws2812@0 {
+		compatible = "worldsemi,ws2812-spi";
+		label = "WS2812";
+
+		/* SPI */
+		reg = <0>; /* ignored, but necessary for SPI bindings */
+		spi-max-frequency = <4000000>;
+
+		/* WS2812 */
+		chain-length = <8>; /* number of LEDs */
+		spi-one-frame = <0x70>;
+		spi-zero-frame = <0x40>;
+	};
+};
+
+/ {
+	chosen {
+		zmk,underglow = &led_strip;
+	};
+};