message: chore(sdk-core): extract webhooks interface
  adds interface for iWebhooks
  Ticket:
diff: +export interface AddOptions {
  + url: string;
  + type: 'block' | 'wallet_confirmation';
  + label?: string;
  + numConfirmations?: number;
  +}
  +
  +export interface RemoveOptions {
  + url: string;
  + type: 'block' | 'wallet_confirmation';
  +}
  +
  +export interface ListNotificationsOptions {
  + prevId?: string;
  + limit?: number;
  +}
  +
  +export interface SimulateOptions {
  + webhookId: string;
  + blockId: string;
  +}
  +
  export interface IWebhooks {
  - placehold: unknown;
  + list(): Promise<any>;
  + add(url: undefined, type: undefined, label: undefined, numConfirmations: undefined): Promise<any>;
  + remove(params: RemoveOptions): Promise<any>;
  + listNotifications(params: ListNotificationsOptions): Promise<any>;
  + simulate(params: SimulateOptions): Promise<any>;
  }
  