commands.push: use "pushloc" path attribute Path instances now have a "pushloc" attribute that exposes the path to be used for pushing. The "default-push" path is automatically captured in the "pushloc" attribute of the "default" path. Drop references to "default-push" and use the "pushloc" attribute for looking up where to push to.

ui: capture push location on path instances Currently, we treat "default" and "default-push" as separate paths, even though they are the same logical entity but with different paths for different operations. Because they are the same entity and because we will eventually be implementing an official mechanism for declaring push URLs for paths, we establish a "pushloc" attribute on path instances. We populate this attribute on the "default" path with the "default-push" value, if present. This will enable consumers stop referencing "default-push" which will make their code simpler.