Update sandbox endpoints to accept Icelandic borrowers

Changes

This update modifies the sandbox endpoints to adjust the supported countries, now including Iceland (ISL), and reorders other country codes.

Updated endpoints

• GET /sandbox/business-generator

  • Updated the country query parameter enum to replace 'MAF' with 'ISL'.
  • Adjusted the order of other country codes accordingly and added 'REU'.

• GET /sandbox/iban-generator

  • Updated the country query parameter enum similarly to include 'ISL' instead of 'MAF'.
  • Added 'REU' as a new supported country code.

• POST /sandbox/invoice-generator

  • Modified the country enum in the GenerateInvoiceRequest schema to include 'ISL' instead of 'MAF'.
  • Reordered other countries and added 'REU'.