SocketsHttpHandler is missing unknown request url scheme validation on redirects

[MihaZupan]

We're validating that we're not following a redirect from https to http.

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/RedirectHandler.cs

Lines 133 to 134 in 5ebfca2

	// Disallow automatic redirection from secure to non-secure schemes
	if (HttpUtilities.IsSupportedSecureScheme(requestUri.Scheme) && !HttpUtilities.IsSupportedSecureScheme(location.Scheme))

We should also check that the new request url scheme is valid at all, as we do before sending the initial request

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/SocketsHttpHandler.cs

Lines 680 to 683 in 5ebfca2

	if (!HttpUtilities.IsSupportedScheme(requestUri.Scheme))
	{
	return new NotSupportedException(SR.Format(SR.net_http_unsupported_requesturi_scheme, requestUri.Scheme));
	}

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