Implement the invoice-line-number API

Overview: The invoice needs a human readable number for the invoice line. This will be known as the FOLIO invoice line number and identifies each line on a given invoice.

Requirements:
Invoice Line Number Format

• This should just be a line number NOT one that includes the invoice number as well
• System Generated
• Should be sequential
• Should not be editable by user
• Must start at 1 and increase by whole numbers
• It will not include the invoice or vendor invoice number

Approach:

• Create a sequence for each invoice and clean it up once we're done with it - much like what's done for po-lines-numbers in mod-orders-storage
• When an invoice is created (POST /invoice-storage/invoices, create a sequence named the UUID of the invoice.
• When GET /invoice-storage/invoice-line-numbers?invoiceId=XYZ is called, get the next value from the sequence associated with the specified invoice ID (UUID)
• When an invoice is closed (PUT /invoice-storage/invoices/<id>, with status == PAID or CANCELLED, delete the sequence associated with the invoice
• When an invoice is being deleted, delete the sequence associated with the invoice
• Reuse the sequence_number schema used by the invoice-number API

Acceptance Criteria:

• The GET /invoice-storage/invoice-line-numbers API is implemented
• The POST /invoice-storage/invoices, PUT /invoice-storage/invoices/<id> and DELETE /invoice-storage/invoices/<id> behavior has been adjusted as described above
• Unit test coverage on new code is at or above 80%