LibTLS: Support empty SNI data in ServerHello

According to RFC6066, empty extension_data for an SNI extension is
absolutely one of the possibilities - so let's support this instead of
spamming the debug log.

Userland/Libraries/LibTLS/TLSv12.h

@@ -175,6 +175,10 @@ enum class HandshakeExtension : u16 {
     SignatureAlgorithms = 0x0d,
 };
 
+enum class NameType : u8 {
+    HostName = 0x00,
+};
+
 enum class WritePacketStage {
     Initial = 0,
     ClientHandshake = 1,