Approve one or more credit memos

This endpoint allows bulk approval of credit memos. Each credit memo is processed independently,
enabling partial success scenarios where some credit memos may be approved while others fail validation.

Conditions:

• Only credit memos with status 'Draft' or 'Pending Approval' can be approved.

Effects of approval:

• Credit memo status is updated to 'Approved'.
• All related Credit Memo Line Items are approved.
• Related Billing Schedule Records and Billing Schedule Details are marked as 'Invoiced'.
• Billing Header Rollup - Total Invoice Amount and Total Pending Amount are updated.