for incoming smtp deliveries, track whether tls and requiretls was used, and display this in the webmail

we store the tls version used, and cipher suite. we don't currently show that
in the webmail.

webmail/api.json

@@ -1816,6 +1816,27 @@
 						"bool"
 					]
 				},
+				{
+					"Name": "ReceivedTLSVersion",
+					"Docs": "0 if unknown, 1 if plaintext/no TLS, otherwise TLS cipher suite.",
+					"Typewords": [
+						"uint16"
+					]
+				},
+				{
+					"Name": "ReceivedTLSCipherSuite",
+					"Docs": "",
+					"Typewords": [
+						"uint16"
+					]
+				},
+				{
+					"Name": "ReceivedRequireTLS",
+					"Docs": "Whether RequireTLS was known to be used for incoming delivery.",
+					"Typewords": [
+						"bool"
+					]
+				},
 				{
 					"Name": "Seen",
 					"Docs": "",