Make SeqNoAndPrimaryTerm the preferred function

Mark `SeqNoPrimaryTerm` as deprecated and make people use
`SeqNoAndPrimaryTerm` instead. It's the preferred naming in
Elasticsearch.

Notice however that on the wire we still have `seq_no_primary_term`,
see
https://github.com/elastic/elasticsearch/blob/ed5fc8bdb343fa27a23ccb2b91d6bf6bd28cc999/server/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java#L83.

Close #1593

search.go

@@ -458,9 +458,16 @@ func (s *SearchService) TypedKeys(enabled bool) *SearchService {
 	return s
 }
 
-// SeqNoPrimaryTerm specifies whether to return sequence number and
-// primary term of the last modification of each hit.
+// SeqNoPrimaryTerm is an alias for SeqNoAndPrimaryTerm.
+//
+// Deprecated: Use SeqNoAndPrimaryTerm.
 func (s *SearchService) SeqNoPrimaryTerm(enabled bool) *SearchService {
+	return s.SeqNoAndPrimaryTerm(enabled)
+}
+
+// SeqNoAndPrimaryTerm specifies whether to return sequence number and
+// primary term of the last modification of each hit.
+func (s *SearchService) SeqNoAndPrimaryTerm(enabled bool) *SearchService {
 	s.seqNoPrimaryTerm = &enabled
 	return s
 }

xpack_async_search_submit.go

@@ -453,9 +453,16 @@ func (s *XPackAsyncSearchSubmit) TypedKeys(enabled bool) *XPackAsyncSearchSubmit
 	return s
 }
 
-// SeqNoPrimaryTerm specifies whether to return sequence number and
-// primary term of the last modification of each hit.
+// SeqNoPrimaryTerm is an alias for SeqNoAndPrimaryTerm.
+//
+// Deprecated: Use SeqNoAndPrimaryTerm instead.
 func (s *XPackAsyncSearchSubmit) SeqNoPrimaryTerm(enabled bool) *XPackAsyncSearchSubmit {
+	return s.SeqNoAndPrimaryTerm(enabled)
+}
+
+// SeqNoAndPrimaryTerm specifies whether to return sequence number and
+// primary term of the last modification of each hit.
+func (s *XPackAsyncSearchSubmit) SeqNoAndPrimaryTerm(enabled bool) *XPackAsyncSearchSubmit {
 	s.seqNoPrimaryTerm = &enabled
 	return s
 }