[Feature Request] Adding the suggested date as a placeholder or a condition

Description Hello, first of all, thanks for the amazing program! :) I'm currently facing an issue and I'm not sure if Paperless is capable of handling it yet. I've read through some feature requests and didn't see this mentioned, so I'm creating my own. There are placeholders for "created" and "added" dates, which is great, but I'm running into a problem: I receive my payslips monthly, but sometimes I wait a while before scanning them, which results in scanning several at once. I've created a workflow that sets the document title to "Payslip Month-Year". However, if I scan four months worth of slips in April, for example, each of them would end up with the same name if I use the "created" or "added" placeholders. It would be great if we could select the suggested date (the one Paperless extracts from the document content) to use as a placeholder instead, including error handling if no date i…