Voucher/VoucherLine schema updates

Overview:
As voucher generation is starting to come together we need to make several adjustments to the schemas:

Voucher schema updates:

• remove voucherLines from voucher
• rename voucherStatus -> status
• rename voucherType -> type
• rename voucherAmount -> amount

VoucherLine Schema updates:

• add voucherId
• remove fundId (captured in fundDistribution)
• rename voucherLineAmount -> amount
• rename sourceId -> sourceIds changing type string to array (there could be many invoice lines against a single voucher line. These are group on a voucher line based on "External account number". See example in MODINVOICE-34)
• fundDistribution needs to be an array of fundDistirbution objects

Acceptance Criteria:

• the schemas are updated
• schema examples are updated
• sample data is updated (if applicable)
• unit and API tests have been updated as needed