Use a 'number' input type for number fields in registrar creation

No tests for this since we don't have any to begin with

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=252508756

java/google/registry/ui/soy/registrar/RegistrarCreateConsole.soy

@@ -223,6 +223,7 @@
         {param name: 'ianaId' /}
         {param value: $ianaId /}
         {param placeholder: 'required' /}
+        {param type: 'number' /}
         {param description kind="text"}
           Registrar IANA ID.
         {/param}