zephyr/modbluetooth_zephyr: Allow BLE to create services at runtime.

This commit adds the required functionality for a peripheral to create
services at runtime, using `BLE.register_services()`.

The feature is enabled on the nrf52840dk_nrf52840 board.

Note that the `CONFIG_BT_GATT_ENFORCE_SUBSCRIPTION=n` option must be used
so that BLE notifications/indications can be sent even if not subscribed.

Signed-off-by: danicampora <[email protected]>

Author: danicampora

ports/zephyr/boards/nrf52840dk_nrf52840.conf

@@ -1,8 +1,13 @@
 CONFIG_NETWORKING=n
 CONFIG_BT=y
 CONFIG_BT_DEVICE_NAME_DYNAMIC=y
+CONFIG_BT_GATT_DYNAMIC_DB=y
 CONFIG_BT_PERIPHERAL=y
 CONFIG_BT_CENTRAL=y
+CONFIG_BT_GATT_CLIENT=y
+CONFIG_BT_L2CAP_TX_MTU=252
+CONFIG_BT_BUF_ACL_RX_SIZE=256
+CONFIG_BT_GATT_ENFORCE_SUBSCRIPTION=n
 
 CONFIG_MICROPY_HEAP_SIZE=98304
 CONFIG_MAIN_STACK_SIZE=8192