php8.0: Compatibility fixes

api/controllers/Circuits.php

api/controllers/Prefix.php

api/controllers/Responses.php

api/controllers/Subnets.php

app/admin/authentication-methods/check-connection.php

app/admin/circuits/edit-logical-circuit-submit.php

app/admin/devices/edit-snmp.php

app/admin/devices/edit.php

app/admin/groups/ad-search-group-result.php

app/admin/groups/edit-group-result.php

app/admin/import-export/import-ipaddr-check.php

app/admin/import-export/import-load-data.php

app/admin/import-export/import-subnets-check.php

app/admin/import-export/import-verify.php

app/admin/nameservers/edit.php

app/admin/nameservers/index.php

app/admin/powerDNS/domain-edit-result.php

app/admin/powerDNS/record-edit.php

app/admin/ripe-import/import-subnets.php

app/admin/sections/edit-order-result.php