php8: Compatibility fixes

README.md

api/controllers/Addresses.php

api/controllers/Circuits.php

api/controllers/Common.php

api/controllers/Devices.php

api/controllers/L2domains.php

api/controllers/Prefix.php

api/controllers/Search.php

api/controllers/Sections.php

api/controllers/Subnets.php

api/controllers/Tools.php

api/controllers/User.php

api/controllers/Vlans.php

api/controllers/Vrfs.php

api/index.php

app/tools/devices/all-devices-filter.php

functions/PEAR/OLE/ChainedBlockStream.php

functions/PEAR/OLE/OLE.php

functions/PEAR/OLE/PPS.php

functions/PEAR/Spreadsheet/Excel/Writer/BIFFwriter.php