feat(debug): allow direct node communication and skip mgmtd node-store lookup when node ip and port is specified.

[pranavpadmasali]

What does this PR do / why do we need it?

Update beegfs debug to accept <node|host:port> as the first positional.
The command first tries to parse a meta/storage entity ID; if parsing fails, it
treats the value as a direct TCP address and sends GenericDebug directly to
that node (without mgmtd node-store lookup). So even if the management is
not running, beegfs CTL can send messages to daemons if the ip address and
ports are known.

This can be helpful during integration tests to ensure that the daemons are running
and to avoid relying on log parsing to confirm that they are listening on the
requested ports.

With this, we can use the debug command to send a debug version message to the node.
If the daemon responds, then it is running; if not, it failed to start as expected.

Also add a shared config.AuthSecret() helper and reuse it in direct debug
requests so auth-secret resolution stays consistent with existing config behaviour.

Are there any specific topics we should discuss before merging?

Not required.

What are the next steps after this PR?

Not required.

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