Swift: Fix false positives in the swift/cleartext-transmission query

[geoffw0]

Fix false positives in the swift/cleartext-transmission query where a tel:, mailto: or similar URL is created that contains unencrypted sensitive data (the telephone number or e-mail address) that is, strictly speaking, transmitted. However in these cases the data is only transmitted by the act of it's use, which is very much intended and unavoidable in creating that connection. This kind of result is therefore not helpful.

[geoffw0]

DCA: we've lost two results, exactly the sort of thing this PR is intended to remove:

                      guard let phoneNumberUrl = URL(string: urlString) else {

(I believe urlString is "tel:" + phoneNumber)
and

          if let url = URL(string: "tel://\(callableNumber)") {

The run was a little slower (15.7%), but wobble on Swift can get that high. I'll keep an eye on the regular run after this is merged just in case. I would expect the query itself to be a bit slower due to one additional data flow being computed, but I would not expect that to meaningfully affect total analysis time.

[redsun82]

Seems very reasonable.

[geoffw0]

Thanks!