Add Oregon National Historic Trail Auto Tour Route shield

[quincylvania]

The mapping is complete but the data is propagating to the tiles. Should be ready to review by morning.

Re: #1101

[quincylvania]

This is now ready for review.

https://www.openstreetmap.org/relation/17706726 https://commons.wikimedia.org/wiki/Category:Signs_of_the_Oregon_National_Historic_Trail

[quincylvania]

Updated with an additional black outline, per #1116.