make sideloading updates during lazy routing optional

[laurelnaiad]

Currently updates are sideloaded within lazy requests. This should be optional behavior. Some clients won't use updates at all.

When not sideloading, detour should send to the server only the knownStates that are relevant to the url being lazy loaded. This means it should determine during URL matching which states are partial URL matches for the requested URL, instead of failing or succeeding altogether. Right now urlMatcher isn't hierarchical in this way, although there is something about a prefix in the code to be investigated.