laptoptop: emacs: navigation: (temporarily) switched back to `project…

…ile`

There are reasons (as I try to keep up with):

- I need to work with large projects, and this eats my time, as `project.el`
  not yet implemented caching functionality. Given that every human being lives
  the single life, it is not practical to be idealist in such cases.

- `project.el` may finally implement caching functionality, and I may switch back
  there, as this is the only reason I could not use it flawlessly, given "large
  projects", mentioned above.

- there are some points of convergence between `project.el` and `projectile`,
  so we should give up decent projects handling functionality altogether, if
  we were purists/idealists/you-name-it, given the initial (political) reason
  for giving up `projectile` in the past.
  See bbatsov/projectile#1591 for example.

- @bbatsov may change his mind about political situation around Ukraine, which
  was the reason mentinoned above. But this is highly doubtful, I think.

machines/laptoptop/default.nix

@@ -330,7 +330,10 @@ in
       wm.enable = true;
     };
     edit.enable = true;
-    navigation.enable = true;
+    navigation = {
+      enable = true;
+      projects.backend = "projectile";
+    };
     history.enable = true;
     misc.enable = true;
   };