* unset XAUTHORITY env var for the networking command
When Teleport passes almost all the environment variables to the child
processes that are born of a reexec. This is an issue when XAUTHORITY is
set as it will be passed to the networking process, causing `xauth` to
use a different file than the one that the SSH session process will use.
This is because the SSH session process only inherits a small subset of
the environment variables from the parent process, and XAUTHORITY is not
one of them. This causes X11 forwarding to fail.
* add Remove method to SafeEnv
* Depguard rules for the session submodule
* Move lib/auditd to session/auditd
* Move lib/loginuid to session/loginuid
* Reduce dependencies of lib/utils/envutils
* Move lib/utils/envutils to session/envutils
* Split the SSH utilities of sshutils/x11 into sshutils/x11forward
* Move lib/sshutils/x11 to session/networking/x11
* Move lib/sshutils/networking to session/networking
* Move lib/shell to session/shell
* Move lib/utils/uds to session/uds
* Move lib/utils/host to session/host
* Move lib/pam to session/pam
* Avoid lib/utils/log in session/pam
* Move lib/service/servicecfg.PAMConfig to session/pam/pamcfg.PAMConfig
* Move lib/srv/uacc to session/uacc
* Avoid importing lib/utils in session/uacc
* Move lib/selinux to session/selinux
* Avoid lib/utils and lib/utils/log in session/selinux
* make go-mod-tidy-all
* Update oss-fuzz path for session/networking/x11
Andrew LeFevre