Make blacklist more specific

[g-ortuno]

Sometimes there are collisions between blacklisted Service UUIDs and non-blacklisted Characteristic UUIDs which results in missing features for Web Bluetooth. For example the FIDO Service (0xfffd) is blacklisted; Playbulb uses that UUID for one of its characteristics which means we can't use the characteristic on Playbulb.

[jyasskin]

Playbulb needs to avoid UUIDs in the Bluetooth reserved space or get them officially allocated by the Bluetooth SIG.

[beaufortfrancois]

I tend to agree with @g-ortuno there. We should blacklist Service 0xfffd, not Characteristic 0xfffd as it is implied in https://github.com/WebBluetoothCG/registries/blob/master/gatt_blocklist.txt