cRPD 23.1+ version specific changes

[mzagozen]

I made two changes in the pre-deploy steps for cRPD version 23.1 and newer:

1. The license file is no longer expected in /config/license/safenet/junos_sfnt.lic, but rather in the parent directory. So it becomes just /config/license/junos_sfnt.lic.
2. It is no longer required to edit the /etc/sshd_config directly and restart SSHD. The startup config for enabling SSH server and allowing root login are honored when the control plane starts.

Implementing this is straightforward, but I am having trouble coming up with a way of keeping backwards compatibility by conditioning behavior on the version. The current cRPD version is available the container image in /etc/junos/release.txt as a string on a single line. But reading this file requires a running container, so not available yet in the pre-deploy stage. Starting a (separate) container just to read the file and grab the would work, but feels very hacky ... WDYT?

[hellt]

Regarding the license, it seems it should be possible to use the cli command (#1350) to load one.
Maybe this is version-agnostic enough to work with pre 23 and post 23 versions?

[hellt]

done in #2014