php8: Compatibility fixes

api/controllers/Common.php

api/index.php

app/admin/import-export/import-recompute-logic.php

app/admin/import-export/import-recompute-preview.php

app/sections/user-menu.php

app/tools/search/search-results-export.php

app/tools/search/search-results.php

app/tools/search/search_results/search-results_addresses.php

app/tools/search/search_results/search-results_circuits.php

app/tools/search/search_results/search-results_customers.php

app/tools/search/search_results/search-results_pstn.php

app/tools/search/search_results/search-results_subnets.php

app/tools/search/search_results/search-results_vlans.php

app/tools/search/search_results/search-results_vrfs.php

functions/classes/class.Params.php

functions/classes/class.User.php

functions/functions.php