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.sum

@@ -89,8 +89,11 @@ github.com/btcsuite/btcd/chaincfg/chainhash v1.0.0/go.mod h1:7SFka0XMvUgj3hfZtyd
 github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1/go.mod h1:7SFka0XMvUgj3hfZtydOrQY2mwhPclbT2snogU7SQQc=
 github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0 h1:59Kx4K6lzOW5w6nFlA0v5+lk/6sjybR934QNHSJZPTQ=
 github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0/go.mod h1:7SFka0XMvUgj3hfZtydOrQY2mwhPclbT2snogU7SQQc=
-github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f h1:bAs4lUbRJpnnkd9VhRV3jjAVU7DJVjMaK+IsvSeZvFo=
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
+github.com/btcsuite/btclog v0.0.0-20241003133417-09c4e92e319c h1:4HxD1lBUGUddhzgaNgrCPsFWd7cGYNpeFUgd9ZIgyM0=
+github.com/btcsuite/btclog v0.0.0-20241003133417-09c4e92e319c/go.mod h1:w7xnGOhwT3lmrS4H3b/D1XAXxvh+tbhUm8xeHN2y3TQ=
+github.com/btcsuite/btclog/v2 v2.0.0-20241017175713-3428138b75c7 h1:3Ct3zN3VCEKVm5nceWBBEKczc+jvTfVyOEG71ob2Yuc=
+github.com/btcsuite/btclog/v2 v2.0.0-20241017175713-3428138b75c7/go.mod h1:XItGUfVOxotJL8kkuk2Hj3EVow5KCugXl3wWfQ6K0AE=
 github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d/go.mod h1:+5NJ2+qvTyV9exUAL/rxXi3DcLg2Ts+ymUAY5y4NvMg=
 github.com/btcsuite/btcwallet v0.16.10-0.20240912233857-ffb143c77cc5 h1:zYy233eUBvkF3lq2MUkybEhxhDsrRDSgiToIKN57mtk=
 github.com/btcsuite/btcwallet v0.16.10-0.20240912233857-ffb143c77cc5/go.mod h1:1HJXYbjJzgumlnxOC2+ViR1U+gnHWoOn7WeK5OfY1eU=