refactor: move-only: move `FeeEstimateMode` enum to `util/fees.h`

diff --git a/src/policy/feerate.h b/src/policy/feerate.h
index 5994fe99..b89f2e1e 100644
--- a/src/policy/feerate.h
+++ b/src/policy/feerate.h
@@ -9,6 +9,7 @@
 #include <consensus/amount.h>
 #include <serialize.h>
 #include <util/feefrac.h>
+#include <util/fees.h>
 
 
 #include <cstdint>
@@ -17,16 +18,6 @@
 
 const std::string CURRENCY_UNIT = "BTC"; // One formatted unit
 const std::string CURRENCY_ATOM = "sat"; // One indivisible minimum value unit
-
-/* Used to determine type of fee estimation requested */
-enum class FeeEstimateMode {
-    UNSET,        //!< Use default settings based on other criteria
-    ECONOMICAL,   //!< Force estimateSmartFee to use non-conservative estimates
-    CONSERVATIVE, //!< Force estimateSmartFee to use conservative estimates
-    BTC_KVB,      //!< Use BTC/kvB fee rate unit
-    SAT_VB,       //!< Use sat/vB fee rate unit
-};
-
 /**
  * Fee rate in satoshis per virtualbyte: CAmount / vB
  * the feerate is represented internally as FeeFrac
diff --git a/src/util/fees.h b/src/util/fees.h
new file mode 100644
index 00000000..25ca246e
--- /dev/null
+++ b/src/util/fees.h
@@ -0,0 +1,17 @@
+// Copyright (c) The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_FEES_H
+#define BITCOIN_UTIL_FEES_H
+
+/* Used to determine type of fee estimation requested */
+enum class FeeEstimateMode {
+    UNSET,        //!< Use default settings based on other criteria
+    ECONOMICAL,   //!< Force estimateSmartFee to use non-conservative estimates
+    CONSERVATIVE, //!< Force estimateSmartFee to use conservative estimates
+    BTC_KVB,      //!< Use BTC/kvB fee rate unit
+    SAT_VB,       //!< Use sat/vB fee rate unit
+};
+
+#endif // BITCOIN_UTIL_FEES_H