Create voucher on transition to "Approved"

Overview:
When an invoice transitions to "Approved" status, a voucher and associated voucher lines should be generated.

1. Obtain a system generated voucher number via GET /voucher-storage/voucher-number
2. Apply fund distributions and calculate totals for each voucher-line.
   • There's one voucher line for each externalAccountNumber.
   • Multiple funds can have the same externalAccountNumber
3. Apply exchange rate calculations for each voucher-line
4. Calculate voucher-level totals from all of the voucher-line totals (after exchange rate has been applied to each line)
5. For now, ignore invoice adjustments. Adjustments will be covered in a separate story

The JSR 354 JavaMoney API should be used. For now the default currencyExchangeProvider configuration is sufficient. Fine-tuning may take place in later stories.

Example:

Invoice

• currency: EUR
• status: Approved
• total: €40
• invoiceLines:
  • InvoiceLine-1
    • total: €10
    • fundDistributions:
      • FD001 - Fund A: 50%
      • FD002 - Fund B: 50%
  • InvoiceLine-2
    • total: €10
    • fundDistributions:
      • FD003 - Fund B: 50%
      • FD004 - Fund C: 50%
  • InvoiceLine-3
    • total: €20
    • fundDistributions:
      • FD005 - Fund B: 25%
      • FD006 - Fund D: 75%

Fund A

• externalAccountNo: 123456

Fund B

• externalAccountNo: 234567

Fund C

• externalAccountNo: 123456

Fund D

• externalAccountNo: 345678

Voucher

• systemCurrency: USD
• invoiceCurrency: EUR
• exchangeRate: 1.10
• voucherAmount: $44.00
• voucherLines:
  • VoucherLine-1
    • externalAccountNo: 123456
    • sourceIds:
      • UUID of InvoiceLine-1
      • UUID of InvoiceLine-2
    • fundDistributions:
      • FD001 -> Fund A: €5 (InvoiceLine-1)
      • FD004 -> Fund C: €5 (InvoiceLine-2)
    • voucherLineAmount: $11.00
  • VoucherLine-2
    • externalAccountNo: 234567
    • sourceIds:
      • UUID of InvoiceLine-1
      • UUID of InvoiceLine-2
      • UUID of InvoiceLine-3
    • fundDistributions:
      • FD002 -> Fund B: €5 (InvoiceLine-1)
      • FD003 -> Fund B: €5 (InvoiceLine-2)
      • FD005 -> Fund B: €5 (InvoiceLine-3)
    • voucherLineAmount: $16.50
  • VoucherLine-3
    • externalAccountNo: 345678
    • sourceIds:
      • UUID of InvoiceLine-3
    • fundDistributions:
      • FD006 -> Fund D: €15 (InvoiceLine-3)
    • voucherLineAmount: $16.50

I've also attached a text file with more basic examples of an invoice, invoiceLines, funds, voucher, voucherLines in json format: https://issues.folio.org/secure/attachment/18280/voucher_json_example.txt

Acceptance Criteria:

• Vouchers are created as described above upon invoice transition to "Approved"
• Unit tests are updated
• API tests will be handled in a separate story
• JavaMoney is used for calculations and currency exchanges