Add notification GATT service to be notifed by Apple devices

[electricalgorithm]

[electricalgorithm]

Within this issue, we need to resolve the authentication issue of BLE as well. Currently everyone can modify watch's clock via GATT. Let's increase the security level there to enable pairing first.

[electricalgorithm]

Authentication is ready. We can only update CTS with pairing first. The next step is to enable device to capture Apple devices notification BLE data.

[electricalgorithm]

https://developer.apple.com/library/archive/documentation/CoreBluetooth/Reference/AppleNotificationCenterServiceSpecification/Specification/Specification.html

Started the implementation in feat/enable-ancs-ble

[electricalgorithm]

I tried to do it with bluetoothctl on Raspberry Pi, can retrieve the notification UUID but couldn't write to control point to get details:

[Gokhan iPhone:/service0023/char002a]# select-attribute 9FBF120D-6301-42D9-8C58-25E699A21DBD
[Gokhan iPhone:/service0023/char0027]# notify on
Notify started
[CHG] Attribute /org/bluez/hci0/dev_80_96_98_01_CC_BC/service0023/char0027 Value:
  00 10 04 09 37 00 00 00                          ....7...
[Gokhan iPhone:/service0023/char0027]# select-attribute 69D1D8F3-45E1-49A8-9821-9BBDFDAAD9D9
[Gokhan iPhone:/service0023/char0024]# write 00 37 00 00 00 01 20 00 03 00 01 04
Attempting to write /org/bluez/hci0/dev_80_96_98_01_CC_BC/service0023/char0024
Failed to write: org.bluez.Error.NotSupported
[Gokhan iPhone:/service0023/char0024]# write 00 37 00 00 00 01 20 00
Attempting to write /org/bluez/hci0/dev_80_96_98_01_CC_BC/service0023/char0024
Failed to write: org.bluez.Error.NotSupported

P.S. This does not work on Macbooks since CoreBluetooth seems to automatically behave like a central role.