feat: Add support for extra sshd_config parameters via 'Include' file (#19842)

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

docker/root/etc/s6/openssh/setup

@@ -49,6 +49,7 @@ if [ -d /etc/ssh ]; then
     SSH_DSA_CERT="${SSH_DSA_CERT:+"HostCertificate "}${SSH_DSA_CERT}" \
     SSH_MAX_STARTUPS="${SSH_MAX_STARTUPS:+"MaxStartups "}${SSH_MAX_STARTUPS}" \
     SSH_MAX_SESSIONS="${SSH_MAX_SESSIONS:+"MaxSessions "}${SSH_MAX_SESSIONS}" \
+    SSH_INCLUDE_FILE="${SSH_INCLUDE_FILE:+"Include "}${SSH_INCLUDE_FILE}" \
     SSH_LOG_LEVEL=${SSH_LOG_LEVEL:-"INFO"} \
     envsubst < /etc/templates/sshd_config > /etc/ssh/sshd_config
 

docker/root/etc/templates/sshd_config

@@ -41,3 +41,5 @@ Banner none
 Subsystem sftp /usr/lib/ssh/sftp-server
 
 AcceptEnv GIT_PROTOCOL
+
+${SSH_INCLUDE_FILE}