Allow for self link generation for custom routes

[DtaggartMB]

Reason we need this change.

When doing a Post/Put for a single resource object using a custom route for example POST /locations/48/rooms/ http/1.1 { "data" : { "type" : "rooms", "attributes" : { "name" : "___hxLnCfZU60", "capacity" : 100, "description" : "Generated by automation using the v5 endpoint" } } }

/location/{id}/rooms where a room was being created, the generated return self link would be generated as /locations/48/rooms/ rather then the expected /locations/48/rooms/{roomid}

What we did was look to see if the returned resource was a collection type, if it isn't it would look for a ID to try to generate that self link. We used the override-able method BuildCanonicalPath to generate the link. If using the default logic the link would generate as /rooms/{id} which is the standard way if you dont have it stacked within another route. Since we do have a custom route our override method produces the correct output.

Now if we made a request to a get a collection of rooms. /locations/48/rooms/ the logic will default the self to the original requesting url/locations/48/rooms/