feat: Add WPM calculator and display widget

app/include/zmk/display/widgets/wpm_status.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <lvgl.h>
+#include <kernel.h>
+
+struct zmk_widget_wpm_status {
+    sys_snode_t node;
+    lv_obj_t *obj;
+};
+
+int zmk_widget_wpm_status_init(struct zmk_widget_wpm_status *widget, lv_obj_t *parent);
+lv_obj_t *zmk_widget_wpm_status_obj(struct zmk_widget_wpm_status *widget);

app/include/zmk/events/wpm_state_changed.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr.h>
+#include <zmk/event_manager.h>
+#include <zmk/wpm.h>
+
+struct zmk_wpm_state_changed {
+    int state;
+};
+
+ZMK_EVENT_DECLARE(zmk_wpm_state_changed);

app/include/zmk/wpm.h

@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+int zmk_wpm_get_state();