Allow ApprovedInvoices to be marked as paid automatically

There would have to be some way to resolve ApprovedInvoices automatically. The process would go like this:
1. Import payments - You provide file for this (generated by bank)
2. Hit backend with the file
3. Backend resolves + returns some results (what was resolved etc.)
4. UI updates its state

The issue does not name any files, tests, or entry points. First clarify the bank-file format, backend endpoint and response, matching rules for ApprovedInvoices, and the UI state changes; done should include an agreed end-to-end workflow and acceptance criteria.

Written by the indexing model from the issue text.