Clean up common user modules

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

users/configs/git/default.nix

@@ -0,0 +1,26 @@
+{ user ? throw "user argument is required" }: { pkgs, ... }:
+
+{
+  home-manager.users."${user.name}" = {
+    programs.git = {
+      enable = true;
+      lfs.enable = true;
+      userName = user.fullName;
+      userEmail = user.email;
+      signing = {
+        signByDefault = true;
+        key = null;
+      };
+      extraConfig.credential.helper = "store";
+      hooks = let
+        commit-msg-hook = pkgs.writeShellScriptBin "git-commit-msg" ''
+          git interpret-trailers --if-exists doNothing --trailer \
+            "Signed-off-by: $(git config user.name) <$(git config user.email)>" \
+            --in-place "$1"
+        '';
+      in {
+        commit-msg = "${commit-msg-hook}/bin/git-commit-msg";
+      };
+    };
+  };
+}