allow filtering fee recipient logs by topic (#5320)

Add separate log topic for `Refreshing fee recipient` messages.

beacon_chain/spec/eth2_apis/dynamic_fee_recipients.nim

@@ -1,9 +1,18 @@
+# beacon_chain
+# Copyright (c) 2022-2023 Status Research & Development GmbH
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
 import
   std/tables,
   stew/results,
   chronicles,
   ../datatypes/base
 
+logScope: topics = "fee_recipient"
+
 type
   Entry = object
     recipient: Eth1Address