Support onboarding & Drop faucet (#119)

* Renaming

* Add server-side support for onboarding

* add onboard --amount command

* support client side onboarding

* Drop dummy tx builder

* Drop faucet

* Fixes

* fix public key encoding

* fix schnorr pub key check in validation

* fix server/README to accomodate onboarding

---------

Co-authored-by: Louis <louis@vulpem.com>
Co-authored-by: João Bordalo <bordalix@users.noreply.github.com>

server/internal/core/domain/payment.go

@@ -28,6 +28,14 @@ func NewPayment(inputs []Vtxo) (*Payment, error) {
 	return p, nil
 }
 
+func NewPaymentUnsafe(inputs []Vtxo, receivers []Receiver) *Payment {
+	return &Payment{
+		Id:        uuid.New().String(),
+		Inputs:    inputs,
+		Receivers: receivers,
+	}
+}
+
 func (p *Payment) AddReceivers(receivers []Receiver) (err error) {
 	if p.Receivers == nil {
 		p.Receivers = make([]Receiver, 0)