[Impeller] eliminate PathReceiver.PathEnd #169719

There is only one path receiver that uses this method and it is only ever used from within the utility helper methods within one class (PathTessellator). In all other classes it is ignored because they don't care about knowing when the path is done. Additionally there are cases where multiple PathSource objects are used together to compose a longer path and so while each might think the "path is done" (i.e. send PathEnd()), they would not be correct in those cases.

Rather than make this the responsibility of all PathSource objects to send this final method call, which is ignored in most cases, we should just have the one case where "final processing" is a necessary requirement define that the process of feeding that one object includes letting it know when all of the path segments are done.