Add UDP protocol by default in SNMP client

Set UDP protocol as transport protocol by default on Client
instantiation.

Tested: protocol set as UDP by default when creating subscribers.

```
busctl call xyz.openbmc_project.Network.SNMP /xyz/openbmc_project/network/snmp/manager xyz.openbmc_project.Network.Client.Create Client sq 192.168.1.25 999
s "/xyz/openbmc_project/network/snmp/manager/1"

busctl get-property xyz.openbmc_project.Network.SNMP /xyz/openbmc_project/network/snmp/manager/1 xyz.openbmc_project.Network.Client Address
s "192.168.1.25"

busctl get-property xyz.openbmc_project.Network.SNMP /xyz/openbmc_project/network/snmp/manager/1 xyz.openbmc_project.Network.Client TransportProtocol
s "xyz.openbmc_project.Network.Client.TransportProtocol.UDP"
```

Change-Id: I21aa601519cbfa51db3b21d260e77c46e6383ae7
Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/snmp_client.cpp b/snmp_client.cpp
index 4dc3d57..fc16a34 100644
--- a/snmp_client.cpp
+++ b/snmp_client.cpp
@@ -17,6 +17,8 @@
 {
     this->address(address);
     this->port(port);
+    this->transportProtocol(sdbusplus::server::xyz::openbmc_project::network::
+                                Client::TransportProtocol::UDP);
 
     // Emit deferred signal.
     emit_object_added();
diff --git a/test/test_snmp_client.cpp b/test/test_snmp_client.cpp
index df4ac3f..5868899 100644
--- a/test/test_snmp_client.cpp
+++ b/test/test_snmp_client.cpp
@@ -41,6 +41,9 @@
     std::string objPath = mgrObjPath;
     objPath += "/" + std::to_string(1);
     Client client(bus, objPath.c_str(), manager, "1.1.1.1", 202);
+    EXPECT_EQ(client.transportProtocol(),
+              sdbusplus::server::xyz::openbmc_project::network::Client::
+                  TransportProtocol::UDP);
     EXPECT_EQ(client.address(), "1.1.1.1");
     EXPECT_EQ(client.port(), 202);
     client.address("2.2.2.2");