Basic PTT implementation

Implements a basic PTT key via BLE HID using the optical pulse sensor as input device.

Just hover your hand over the sensor and the card10 will press the configured key. There is a menu to select which key to use and also which report to use.

Currently the keyboard and the consumer control reports are supported. The list of allowed keys is hard coded in the app. A later iteration might use introspection of the to get a list from the Adafruit library.

epicardium/epicardium.h

@@ -236,11 +236,12 @@ API(API_INTERRUPT_IS_ENABLED, int epic_interrupt_is_enabled(api_int_id_t int_id,
 /** BHI160 Magnetometer.  See :c:func:`epic_isr_bhi160_magnetometer`. */
 #define EPIC_INT_BHI160_MAGNETOMETER    8
 /** MAX86150 ECG and PPG sensor.  See :c:func:`epic_isr_max86150`. */
-#define EPIC_INT_MAX86150		9
+#define EPIC_INT_MAX86150               9
 /** Bluetooth Low Energy event.  See :c:func:`epic_isr_ble`. */
 #define EPIC_INT_BLE                    10
+#define EPIC_INT_MAX86150_PROX          11
 /* Number of defined interrupts. */
-#define EPIC_INT_NUM                    11
+#define EPIC_INT_NUM                    12
 /* clang-format on */
 
 /*