Override configs on migration

[mixa3607]

Enable overriding existed *.conf.dpapi.

In current release, on add file to C:\Program Files\WireGuard\Data\Configurations with name that exist, app will go to loop, because can't create already existed file. Log:

2021-10-31 04:33:00.174068: [MGR] Unable to ingest and encrypt `C:\Program Files\WireGuard\Data\Configurations\srv1-over-oracle1.conf`: Cannot create a file when that file already exists.
2021-10-31 04:33:00.175679: [MGR] Unable to ingest and encrypt `C:\Program Files\WireGuard\Data\Configurations\srv1-over-oracle1.conf`: Cannot create a file when that file already exists.
2021-10-31 04:33:00.177246: [MGR] Unable to ingest and encrypt `C:\Program Files\WireGuard\Data\Configurations\srv1-over-oracle1.conf`: Cannot create a file when that file already exists.
....

If my solution is not suitable, I hope that someone will fix the problem differently.