Re: #1290: Add a lotus wallet verify API and CLI command

- The command takes an address, message, and signature, and returns true if the sig is valid

node/impl/full/wallet.go

@@ -2,6 +2,7 @@ package full
 
 import (
 	"context"
+	"github.com/filecoin-project/lotus/lib/sigs"
 
 	"github.com/filecoin-project/go-address"
 	"github.com/filecoin-project/lotus/chain/stmgr"
@@ -53,6 +54,10 @@ func (a *WalletAPI) WalletSignMessage(ctx context.Context, k address.Address, ms
 	}, nil
 }
 
+func (a *WalletAPI) WalletVerify(ctx context.Context, k address.Address, msg []byte, sig *types.Signature) bool {
+	return sigs.Verify(sig, k, msg) == nil
+}
+
 func (a *WalletAPI) WalletDefaultAddress(ctx context.Context) (address.Address, error) {
 	return a.Wallet.GetDefault()
 }