Shields for Guernsey, Jersey and the Isle of Man

[claysmalley]

The British Crown Dependencies of Guernsey, Jersey and the Isle of Man use the same numbering and signage system as the UK (#696). As such, route relations would be a needless complication, and the best approach would be to have OpenMapTiles assign pseudo-networks to these routes based on way refs.

No motorways are present on any of the islands, so there is no need to support the M prefix or blue shield icons.

[ZeLonewolf]

Probably we could just use the existing UK pseudo-networks