Add "end cap angle" capability to "thick linestring" and Roads

From a discussion on [intersection turns/movements](https://github.com/a-b-street/osm2streets/issues/67#issuecomment-1248685070), we talked about the idea of allowing roads to end with an angle other than 90 degrees.

The ability to generate thick linestring and "parallel" geometry with an arbitrary angle at the end will allow us to:

- have roads join intersections at differing angles,
- seamlessly join roads together at `Connection` type intersections.