Allow customizing the system config to include in the tarball

[terlar]

If you build your own custom tarballs this is useful.

[terlar]

@nzbr I hope the ping is not disturbing, just wanted to make sure this one was not missed, seems it requires approval to run the workflows as well. But I have tested this locally and it works.

I don't think it is a controversial change, however, I was slightly unsure about the option name.

[terlar]

Not sure if this is cleaner or not, I had to add wrapping parenthesis around the whole string to get it to work

[terlar]

Would it make sense to chown these files to the defaultUser and add write permissions? I just tested this and in order to modify these after the install I first had to do that, or edit the files via sudo and force write, since it didn't have write permissions configured.

sudo chown -R ${config.wsl.defaultUser} etc/nixos
sudo chmod -R u+w etc/nixos

What do you think?

This should go for both cases. At least the write permission seems like something you'd like even if the files are owned by root.

[SuperSandro2000]

This is the standard nixos configuration and I am not sure if we should change that.

[nzbr]

I don't think the default user should be able to write the config, but giving root write permissions on the files would definitely be a good idea (and something I wanted to make an issue for multiple times, but always forgot)

[terlar]

I pushed another commit, giving the root write permissions to the /etc/nixos files. I opted for string interpolation again for this section to avoid parenthesis overload. Let me know if you prefer another style.