Fix throwing data URI requests

[frederikbosch]

Since Capacitor 8.0 data: requests throw because NSURLResponse is not a HTTPURLRepsonse

[theproducer]

Thanks @frederikbosch! Do you have a reproduction for this issue, or can it be seen in basically any minimal project that uses CapacitorHttp?

[frederikbosch]

@theproducer I don't at the moment. I have upgraded my app from 7 to 8 and I got crashes because of the forced casts. It might very well be that because of some other upgrades that I only now started with data: URI requests.

That data URIs fail can be proven quite easily by this SwiftFiddle.

Moreover, it is kind of documented behavior. The URLSession.dataTask method documentation says:

If you are making an HTTP or HTTPS request, the returned object is actually an HTTPURLResponse object.

And a data: URI request is not a HTTP request. But documentation is not clear what the response is if the request is not a HTTP(S) request, but apparently it is a NSURLResponse.

[frederikbosch]

@markemer Much better to unpack the response optional, I have updated the PR.