Upgrade and decrypt database

[kenkendk]

After the RC4 support is no longer present, the best upgrade path seems to load a .Net build with the old SQLite binaries that includes RC4 support. Then use the password to decrypt the database and save it.

However, the build is not compatible with the new Duplicati release, so an optional download may be relevant.
This download could use the signed manifest added as part of #5145

Alternative is to check if we can decrypt the file using .NET support for RC4, so the upgrade can be done without an extra tool.

[kenkendk]

Seems it is straightforward to decrypt without relying on the old SQLite:

https://gist.github.com/zuccaro/562548a7592f011a7b9a

[duplicatibot]

This issue has been mentioned on Duplicati. There might be relevant details there:

https://forum.duplicati.com/t/switching-master-branch-to-net8/17794/1