Improve the documentation for how to migrate data between ServiceControl instances

[timbussmann]

Relevant information

When migrating a ServiceControl instance to a new server or system, it's not obvious how to transfer the data of the existing SC instance to the new SC instance.
It seems that the only approach at the moment seems to just copy the whole database (or create a backup in maintenance mode) (see https://docs.particular.net/servicecontrol/backup-sc-database#important-notes-and-restrictions) which seems to be a brittle approach, as according to our documentation, the instances need to have the same service name (which might not be desired by the user):

When restoring a ServiceControl database, the name of the ServiceControl Windows Service must be the same on the target machine as it was on the source machine.

[WilliamBZA]

There's not much we can do without tying ourselves more the either Esent or Raven.

We can spend some time improving the documentation (perhaps having a dedicated "migrating data" section) on exporting/importing to try make the process clearer - possibly even include some powershell scripts.

[mikeminutillo]

We have guidannce for performing a zero-downtime upgrade which could be extracted and repurposed.