"BN move" tool implementation for corporations

See comment from Vysakh in #25549
"We have implemented BN move for firms, the same thing should work for corporations. But it may not be working at this point. As per Thor "There have been several rounds of firewall changes and server changes, as far as I know they have not kept the uploaded files coming in. To confirm/fix this flow we need help from David Roberts."

This has been discussed with the Home team on Mar 19, 2025 They confirmed that such tool will need to work for the MVP release as there are many instances of "BN moves" and it is used by IT OPS.

If the tool is not in place by MVP release developers will need to do data changes in the database, which will create significant overhead work.

No files, tests, or entry points are named. Start by locating the existing BN move implementation for firms and the corporation workflow, then verify the uploaded-file flow and database changes described in the issue. Done means a corporation BN move tool works for the MVP path without manual database changes.

Written by the indexing model from the issue text.