Add HTTPS port into TXT record

Example: https=123

BUG: 26687064
Change-Id: I8ebba527102eec2f916e6e9239ba07d026de7b7e
Reviewed-on: https://weave-review.googlesource.com/2889
Reviewed-by: Alex Vakulenko <avakulenko@google.com>

src/privet/publisher.cc

diff --git a/src/privet/publisher.cc b/src/privet/publisher.cc
index 55c9fe4..db26b26 100644
--- a/src/privet/publisher.cc
+++ b/src/privet/publisher.cc
@@ -65,6 +65,10 @@
       {"flags=" + WifiSsidGenerator{cloud_, wifi_}.GenerateFlags()},
   };
 
+  if (device_->GetHttpsEnpoint().first > 0)
+    txt_record.emplace_back("https=" +
+                            std::to_string(device_->GetHttpsEnpoint().first));
+
   if (!cloud_->GetCloudId().empty())
     txt_record.emplace_back("gcd_id=" + cloud_->GetCloudId());