feat: Add WPM calculator and display widget

app/tests/wpm/1-single_keypress/events.patterns

@@ -0,0 +1,2 @@
+s/.*wpm_work_handler: //p
+s/.*wpm_event_listener: //p

app/tests/wpm/1-single_keypress/keycode_events.snapshot

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+key_pressed_count 1 keycode 5
+Raised WPM state changed 12 wpm_update_counter 1
+Raised WPM state changed 6 wpm_update_counter 2
+Raised WPM state changed 4 wpm_update_counter 3
+Raised WPM state changed 3 wpm_update_counter 4
+Raised WPM state changed 2 wpm_update_counter 5
+Raised WPM state changed 0 wpm_update_counter 1

app/tests/wpm/1-single_keypress/native_posix.conf

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+CONFIG_KSCAN=n
+CONFIG_ZMK_KSCAN_MOCK_DRIVER=y
+CONFIG_ZMK_KSCAN_GPIO_DRIVER=n
+CONFIG_GPIO=n
+CONFIG_ZMK_BLE=n
+CONFIG_LOG=y
+CONFIG_LOG_BACKEND_SHOW_COLOR=n
+CONFIG_ZMK_LOG_LEVEL_DBG=y
+CONFIG_ZMK_WPM=y

app/tests/wpm/1-single_keypress/native_posix.keymap

@@ -0,0 +1,10 @@
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,10)
+		/* Wait for the worker to trigger and reset after 5 seconds, followed by a 0 at 6 seconds */
+		ZMK_MOCK_PRESS(0,0,6000) 
+	>;
+};