Create a load testing EPP client (#2415)

* Create a load testing EPP client.

This code is mostly based off of what was used for a past EPP load testing client that can be found in Google3 at https://source.corp.google.com/piper///depot/google3/experimental/users/jianglai/proxy/java/google/registry/proxy/client/

I modified the old client to be open-source friendly and use Gradle.

For now, this only performs a login and logout command, I will further expand on this in later PRs to add other EPP commands so that we can truly load test the system.

* Small changes

* Remove unnecessary build dep

* Add gradle build tasks

* Small fixes

* Add an instances setUp and cleanUp script

* More modifications to instance setup scripts

* change to ubuntu instance

* Add comment to make ssh work

load-testing/src/main/java/google/registry/client/resources/login.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
+<command>
+  <login>
+    <clID>@@CLIENT@@</clID>
+    <pw>@@PASSWORD@@</pw>
+    <options>
+      <version>1.0</version>
+      <lang>en</lang>
+    </options>
+    <svcs>
+      <objURI>urn:ietf:params:xml:ns:host-1.0</objURI>
+      <objURI>urn:ietf:params:xml:ns:domain-1.0</objURI>
+      <objURI>urn:ietf:params:xml:ns:contact-1.0</objURI>
+    </svcs>
+  </login>
+  <clTRID>epp-client-login-@@NOW@@-@@CHANNEL_NUMBER@@</clTRID>
+</command>
+</epp>

load-testing/src/main/java/google/registry/client/resources/logout.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
+  <command>
+    <logout/>
+    <clTRID>epp-client-logout-@@NOW@@-@@CHANNEL_NUMBER@@</clTRID>
+  </command>
+</epp>