build: add handler set implementations

This commit then also adds an implementation of the btclog.Handler
interface called `handlerSets` which basically lets us have a Handler
backed by many Handlers (we need one for the stdout and one for our log
file).

go.mod

@@ -9,7 +9,8 @@ require (
 	github.com/btcsuite/btcd/btcutil v1.1.5
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.8
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0
-	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
+	github.com/btcsuite/btclog v0.0.0-20241003133417-09c4e92e319c
+	github.com/btcsuite/btclog/v2 v2.0.0-20241017175713-3428138b75c7
 	github.com/btcsuite/btcwallet v0.16.10-0.20240912233857-ffb143c77cc5
 	github.com/btcsuite/btcwallet/wallet/txauthor v1.3.5
 	github.com/btcsuite/btcwallet/wallet/txrules v1.2.2