[RFE] sshd default config should read drop-ins

[pothos]

Current situation

Customization of the sshd config requires a modification of the original file. While this should work with a regular file we still didn't convert it back from being a symlink to /usr. But even with a regular file, this would mean losing auto updates.

Impact

Customization is hard and loses auto updates.

Ideal future situation

We have Include /etc/ssh/sshd_config.d/*.conf in the default config, so that users can use drop-ins as on, e.g., Fedora.

Implementation options

While at it, also stop using a symlink and instead install the default to /etc (or if the default under /usr works, use that and have nothing in /etc).

Additional information

[tormath1]

FWIW Gentoo has recently made the switch too:

• https://www.gentoo.org/support/news-items/2023-05-11-openssh.html
• gentoo/gentoo@51642f0

[dongsupark]

Moved to backlog