refactor: Move drivers into properly module.

* Align our driver module layout to properly match Zephyr conventions,
  allowing proper CMake setup to amend the library for each type of driver.

app/module/drivers/sensor/ec11/ec11.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/sys/util.h>
+
+struct ec11_config {
+    const struct gpio_dt_spec a;
+    const struct gpio_dt_spec b;
+
+    const uint16_t steps;
+    const uint8_t resolution;
+};
+
+struct ec11_data {
+    uint8_t ab_state;
+    int8_t pulses;
+    int8_t ticks;
+    int8_t delta;
+
+#ifdef CONFIG_EC11_TRIGGER
+    struct gpio_callback a_gpio_cb;
+    struct gpio_callback b_gpio_cb;
+    const struct device *dev;
+
+    sensor_trigger_handler_t handler;
+    const struct sensor_trigger *trigger;
+
+#if defined(CONFIG_EC11_TRIGGER_OWN_THREAD)
+    K_THREAD_STACK_MEMBER(thread_stack, CONFIG_EC11_THREAD_STACK_SIZE);
+    struct k_sem gpio_sem;
+    struct k_thread thread;
+#elif defined(CONFIG_EC11_TRIGGER_GLOBAL_THREAD)
+    struct k_work work;
+#endif
+
+#endif /* CONFIG_EC11_TRIGGER */
+};
+
+#ifdef CONFIG_EC11_TRIGGER
+
+int ec11_trigger_set(const struct device *dev, const struct sensor_trigger *trig,
+                     sensor_trigger_handler_t handler);
+
+int ec11_init_interrupt(const struct device *dev);
+#endif