Include a "Partially Paid" status in Sales Invoice

[lxnow]

Currently, the Sales Invoice form shows the form status as it relates to accounts receivable, including paid, overdue, draft, and so on:

For invoices that have been partially paid for but are not yet completely paid, the status is normally kept at unpaid or overdue depending on the due date. Feature request is to have new statuses called partially paid and partially paid overdue. This will be helpful for businesses that are trying to get a quick eyeball on the most important invoices that are not yet paid (at all) versus invoices that have been partially paid but still have balance to collect.

partially paid == (total due < unpaid amount OR paid amount > 0 but less than total due) AND due_date is <= today()
partially paid overdue == (total due < unpaid amount OR paid amount > 0 but less than total due) AND due_date is > today()

[sagarvora]

This has been done partly (pun intended) in #27625. We didn't introduce a Partly Paid Overdue status, but the Overdue status was extended to cases when one of the payments in Payment Schedule is overdue.

[stale]

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