clan tests: allow testing CLI interactions

This is an improvement of the clanTest nixos vm test module.

The module now has a new option clan.test.fromFlake that allows to specify a flake.nix as the source for the test clan instead of specifying clan.XXX options.

This in turn allows accessing the `flake.nix` inside the test driver allowing to use the clan cli on it

lib/test/minify.nix

@@ -8,4 +8,5 @@
   nix.registry = lib.mkForce { };
   documentation.doc.enable = false;
   documentation.man.enable = false;
+  documentation.enable = lib.mkDefault false;
 }