openconnect: T6500: add support for multiple ca-certificates (#3691)
Add possibility to provide a full CA chain to the openconnect server.
- Support multiple CA certificates
- For every CA certificate specified, always determine the full certificate chain in the background and add the necessary SSL certificates
(cherry picked from commit 973f06c00b902c43dfea34bdf01bdec7c599c452)
Co-authored-by: Christian Breunig <christian@breunig.cc>