add a new internal hook to save ssh log (#15787)

* add a new internal hook to save ssh log

as title, when a ssh error ocure like #15785.
only when switch ``RUN_MODE`` to dev can we
found which error is ocure. But this way is
not a good idea for production envirment.

this changes try save ssh error mesage to the
log file like other log by a new internal hook.
I think it's usefull for find error message
in production envirment. Thanks.

Signed-off-by: a1012112796 <1012112796@qq.com>

* rename and fix nit

* Update modules/private/hook.go

Co-authored-by: silverwind <me@silverwind.io>

Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/setting/log.go

@@ -287,6 +287,7 @@ func newLogService() {
 
 	options := newDefaultLogOptions()
 	options.bufferLength = Cfg.Section("log").Key("BUFFER_LEN").MustInt64(10000)
+	EnableSSHLog = Cfg.Section("log").Key("ENABLE_SSH_LOG").MustBool(false)
 
 	description := LogDescription{
 		Name: log.DEFAULT,

modules/setting/setting.go

@@ -319,6 +319,7 @@ var (
 	DisableRouterLog   bool
 	RouterLogLevel     log.Level
 	EnableAccessLog    bool
+	EnableSSHLog       bool
 	AccessLogTemplate  string
 	EnableXORMLog      bool