Generate routes definition for easier redirect and goto

[chientrm]

Generate .svelte-kit/routes.ts from the dir tree src/routes so that it's easier to redirect at server-side and goto at client-side and less likely to get to the wrong route.

Example routes.ts

[smblee]

I use ts-routes for this. Would definitely be nice for autogeneration, but it also hasn't been too much hassle to manage on my own with this lib.