Allow setting DS records in create_domain and update_domain

The DS records consist of 4 values:
- keyTag: unsigned short (2 bytes)
- alg: unsigned byte
- digestType: unsigned byte
- digest: binary hex

NOTE: the current CL doesn't support keyData, neither as the optional field in dsData nor as a replacement for dsData

The command tool accepts DS records as a string, where the 4 values are given
as one string separated by white-spaces as follows:
<keyTag> <alg>  <digestType>  <digest>

e.g. something like:
60485 5  2  D4B7D520E7BB5F0F67674A0CCEB1E3E0614B93C4F9E99B8383F6A1E4469DA50A

which is how it's written in Zone files, allowing easy copy-paste from existing values.
ommas is confusing when using spaces.

The various "numbers" (keyTag, alg, digestType) are only checked that they are
positive integers - the rest is left for the server.

digest it checked to be an even-lengthed hex string.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=184583068

java/google/registry/tools/soy/DomainCreate.soy

@@ -24,6 +24,7 @@
   {@param admins: list<string>}
   {@param techs: list<string>}
   {@param password: string}
+  {@param dsRecords: list<[keyTag:int, alg:int, digestType:int, digest:string]>}
 
   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
@@ -53,6 +54,20 @@
           </domain:authInfo>
         </domain:create>
       </create>
+      {if length($dsRecords) > 0}
+        <extension>
+          <secDNS:create xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1">
+            {for $dsRecord in $dsRecords}
+              <secDNS:dsData>
+                <secDNS:keyTag>{$dsRecord.keyTag}</secDNS:keyTag>
+                <secDNS:alg>{$dsRecord.alg}</secDNS:alg>
+                <secDNS:digestType>{$dsRecord.digestType}</secDNS:digestType>
+                <secDNS:digest>{$dsRecord.digest}</secDNS:digest>
+              </secDNS:dsData>
+            {/for}
+          </secDNS:create>
+        </extension>
+      {/if}
       <clTRID>RegistryTool</clTRID>
     </command>
   </epp>