message: chore(issuer-api): remove unused types
diff: -export type CertificateAmount = {
  - id: number;
  - amount: string; // Stringified BigNumber
  -};
  -
  -export const TOTAL_AMOUNT = 'TOTAL';
  -
  export enum BlockchainEventType {
  IssuanceSingle = 'IssuanceSingle',
  IssuanceBatch = 'IssuanceBatch',
  