Clef: USB hw wallet support (#17756)

* signer: implement USB interaction with hw wallets

* signer: fix failing testcases

signer/core/api_test.go

@@ -19,6 +19,7 @@ package core
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"math/big"
@@ -41,6 +42,10 @@ type HeadlessUI struct {
 	controller chan string
 }
 
+func (ui *HeadlessUI) OnInputRequired(info UserInputRequest) (UserInputResponse, error) {
+	return UserInputResponse{}, errors.New("not implemented")
+}
+
 func (ui *HeadlessUI) OnSignerStartup(info StartupInfo) {
 }