[now dev] Clean up `dev-router` a bit (#2099)
[now dev] Clean up `dev-router` a bit (#2099)

* [now dev] Clean up `dev-router` a bit

This is a follow up to #2095 to move the `resolveRouteParameters()`
funcrtion to the top-level and other slight optimizations like not
re-parsing the URL multiple times.

* Remove unused `qs` import

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