actionJoinWays doesn't always reverse the ways while joining

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While working on #4589, I found a tricky bug in actionJoinWays.

This code uses osmJoinWays to get the joined nodelist. Unfortunately osmJoinWays has a side effect that it sometimes needs to reverse the ways in order to join them properly. Reversing a way might change the tags of the way, the order of the nodes, but also adjust the tags on the child nodes.

iD/modules/actions/join.js

Lines 40 to 44 in fdf1fa4

	var joined = osmJoinWays(ways, graph)[0];
	survivor = survivor.update({nodes: _map(joined.nodes, 'id')});
	graph = graph.replace(survivor);

The reversed ways and nodes never get replaced into the graph, and the code after osmJoinWays continues working with the original immutable survivor way, when really we need to perform those reversal actions.

Here is a case where we join two ways (Left, Right). Both ways have directional stop signs. What should happen is that osmJoinWays should reverse any tags on the Right way and the Right stop sign so that it continues to face East. (osmJoinWays actually does call actionReverse internally, but it doesn't persist the results of that into the graph. It should not update the graph, but it should return those actions so that the caller can do it if needed).