Add shield for Utah Federal Aid routes

Federal Aid routes of Utah do not have guide signage, but are sometimes signed with mileposts that include the route number in a pentagonal "county" shield.

The definition for `network=US:UT:Wayne` is removed here because it was a mistagging by yours truly, corrected [here.](https://www.openstreetmap.org/changeset/156846582)

src/js/shield_defs.js

@@ -2873,7 +2873,7 @@ export function loadShields() {
       bottom: 5,
     },
   };
-  ["Wayne", "Washington"].forEach(
+  ["FA", "Washington"].forEach(
     (county) =>
       (shields[`US:UT:${county}`] = pentagonUpShield(
         3,