🐛 Resolve string variables in route paths

[savannahostrowski]

Closes #49

This was a good catch. The fix here is to extract string variables to build up a map and then replace matching variable names with extracted paths. This will work for most cases. There is an edge case that I would like to defer, since I think it's pretty uncommon and requires a bunch more complexity:

user_id = "/some/string"

@app.get("/users/{user_id}")
def get_user(user_id:int): ...

This obviously won't work but our resolution logic will incorrectly replace it.

I've also fixed the tooltip to strip unresolvable dynamic prefixes (like settings.API_PREFIX) instead of showing them as if they were path parameters