Expose cluster information via rpc

Co-authored-by: glozow <gloriajzhao@gmail.com>

test/functional/mempool_persist.py

@@ -128,7 +128,8 @@ class MempoolPersistTest(BitcoinTestFramework):
         assert_equal(fees['base'] + Decimal('0.00001000'), fees['modified'])
 
         self.log.debug('Verify all fields are loaded correctly')
-        assert_equal(last_entry, self.nodes[0].getmempoolentry(txid=last_txid))
+        new_entry = self.nodes[0].getmempoolentry(txid=last_txid)
+        assert_equal({**last_entry, "clusterid": None}, {**new_entry, "clusterid": None})
         self.nodes[0].sendrawtransaction(tx_prioritised_not_submitted['hex'])
         entry_prioritised_before_restart = self.nodes[0].getmempoolentry(txid=tx_prioritised_not_submitted['txid'])
         assert_equal(entry_prioritised_before_restart['fees']['base'] + Decimal('0.00009999'), entry_prioritised_before_restart['fees']['modified'])