Own certificate upload during initial setup wizard

Allow uploading own CA certificate during wizard setup. This will have influence on the edge adoption since the TLS setup will be skipped.

This requires the following modifications:
- [ ] Enable option to upload certificate (already implemented but disabled)
- [ ] If uploading certificate, instruct user of the manual actions that need to be performed
- [ ] The adoption should not try to setup the TLS, but verify if it can connect with the proxy with given certificate
- [ ] Currently proxy detects if it needs adoption when it has certificates present in a folder. This needs to be modified, as we now assume that the user may upload their own certificates but the proxy should still wait for adoption (which would only check if the connection can be established, as mentioned above)