Update device advert scanning functionality

[thegecko]

The specification outlines a (not yet stable) ability to watch a device's adverts:

https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothdevice-watchadvertisements

This likely needs quite a refactor of the noble adapter code to continually scan for devices and read the adData for a specific device.

Implement:

• BluetoothDevice.watchAdvertisements()
• BluetoothDevice.unwatchAdvertisements()
• BluetoothDevice.watchingAdvertisements

Remove:

• BluetoothDevice.adData

Update:

• Eddystone example

[m4-miranda]

Hi, fairly new to the project and the spec, is this functionality built into Chrome? How would one go about contributing?

[thegecko]

The implementation status suggests this isn't supported in Chrome yet.
That doesn't mean you can't implement it following the specification, but there's no way to then compare it with another implementation.

[tavrez]

I need to read a payload of a services on a non-connectable device, is this the method needed for my work?