refactor: split common/nixos.nix and -/home.nix

Split these big files into modular files that
are easier to share and read on their own.

profiles/common/home/git.nix

@@ -0,0 +1,39 @@
+{ ... }:
+{
+  programs.git = {
+    enable = true;
+    aliases = {
+      a = "add";
+      c = "commit";
+      cl = "clone";
+      co = "checkout";
+      b = "branch";
+      i = "init";
+      m = "merge";
+      s = "status";
+      r = "restore";
+      p = "pull";
+      pp = "push";
+    };
+    signing = {
+      key = "0x76FD3810215AE097";
+      signByDefault = true;
+    };
+    userEmail = "leon.schwarzaeugl@gmail.com";
+    userName = "Swarsel";
+    difftastic.enable = true;
+    lfs.enable = true;
+    includes = [
+      {
+        contents = {
+          github = {
+            user = "Swarsel";
+          };
+          commit = {
+            template = "~/.gitmessage";
+          };
+        };
+      }
+    ];
+  };
+}