feat: improve ssh settings

[redtux]

Setting up an SSH connection inside the launcher is imho more complicated than needed, i.e. at the moment I need to enter more SSH settings than normally needed.

It would be great if at least on GNU/Linux systems (and probably on macOS systems as well) the user's local SSH config was used.

Personally, I manually connect to my node via ssh <host>. The SSH client than reads all required parameters from my ~/.ssh/config (and its includes).

Therefore, I'd expect the launcher to accept as SSH hostname without additionally having to provide username, port, and key file / identity file.

Further more it would be great if users could browse the keyfile in the app. It might not be trivial to copy&paste the path for people that are not used to the command line (= the target audience). E.g. copying the path in Nautilus / Gnome file manager imho is not easy.

Last but not least: When enabling the option "Use SSH key authentication" it should say "Full path to keyfile location" or sth. as snap will not resolve ~/.ssh/id_ed25519_stereum as /home/redtux/.ssh/id_ed25519_stereum - and will instead throw an error saying no such file or directory, open ~/.ssh/id_ed25519_stereum.

[redtux]

As discussed, I can confirm that the fix for #108 is working, but now I am getting the above error that seems ssh related.