Hotfix against "OTA of large files results in device hangs" (#7458)
Also includes backports from 3.0.0-dev:
- boards: 4dsystems (gen4iod) updates (#7433)
- Free space of overwritten files in LittleFS (#7434)
- Keep client certs when server authentication set (#7464)
- CVE-2020-12638 workaround for WPA downgrade attack (#7486)
- Initialize _ledPin (#7487)
- Correct stack string buffer length (#7488)
