This updates the minimal supported version of CMake to 3.16, which in turn enables us to use more CMake features and have a cleaner build system.
This is the version that provides most new features and also the one we use in our latest docker image for CI.
The existing Bluetooth examples are split as:
1. examples/bluetooth/bluedroid - Bluedroid Host (BT + BLE) examples
a. examples/bluetooth/bluedroid/classic_bt - Classic BT examples
b. examples/bluetooth/bluedroid/ble - BLE examples
c. examples/bluetooth/bluedroid/coex - Classic BT and BLE coex examples
d. examples/bluetooth/bluedroid/hci - VHCI and HCI UART examples
i. Rename ble_adv to controller_vhci_ble_adv and move it in hci folder
2. examples/bluetooth/nimble - NimBLE BLE Host + NimBLE Mesh examples
3. examples/bluetooth/esp_ble_mesh - ESP BLE Mesh examples
4. Update documentation references