Fixed bug with host route match rule

[stackoverfloweth]

I discovered bug while trying to update our stackblitz to latest version (currently on 0.2.0). Initial routes were not passing routeHostMatches because url has localhost:5173 for host and route would have undefined.

This PR updates the logic for host match rule to treat a route without host as automatically relative and passes host check.

At some point as we expand support for external routes we can expect route to have host, however undefined will continue to be assumed as automatically relative so this change will still apply.

[netlify[bot]]

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