Request: literally create files

[upidapi]

Description

Add some way to create literal files (not just symlinks to files). This might be achievable by adding "home.file.<name>.mode", like environment.etc does for it's files. Where the default value is "symlink" but if you set to to, for example 700. Then it would just create a file with said permission (700).

Why?

This would be nice to have for files that programs feel a need to write to, but you need some default value/text, and you don't want to save the programs changes. You cant just use .source = (mkOutOfStoreSymlink "your-config/some-file"). Since this would propegate the changes that the program does to your config.

An example of where this would be nice is Vesktop. Where .config/vesktop/state.json has to have the field "firstLaunch" to avoid the welcome / initial config screen. But Vesktop writes to this file to save some other stuff like window pos/size etc. So id like to avoid having those changes show in my config since it dirties the git history.

The alternative is something like this:

    # vesktop checks if state.json has the "firstLaunch" to
    # determin if it should show the "Welcome to vesktop" page
    home.activation = {
      # We have to do it like this since vesktop needs be able to
      # write to it (a symlink to the store would have been unwritabe)
      # If vesktop cant write to it then it chrashes
      createVesktiopStateJson = let
        state_path = "~/.config/vesktop/state.json";
        data = builtins.toJSON {
          # (the other setting dont matter)
          firstLaunch = false; # the value of this is ignored lol
        };
      in
        lib.hm.dag.entryAfter ["linkGeneration"] ''
          echo '${data}' > ${state_path}
        '';
    };