feat(nvim): add vim-zoom

Add https://github.com/dhruvasagar/vim-zoom so that I can focus on a
single split within Vim in the same way I can zoom to a tmux pane.

system/shared/home-manager.nix

@@ -70,6 +70,17 @@ let
       sha256 = "n8jd6fy30XukZ9NFZX5qclSlMfziP/Ew9dXfkysRl4Y=";
     };
   };
+
+  vim-zoom = pkgs.vimUtils.buildVimPlugin {
+    name = "vim-zoom";
+    src = pkgs.fetchFromGitHub {
+      owner = "dhruvasagar";
+      repo = "vim-zoom";
+      rev = "01c737005312c09e0449d6518decf8cedfee32c7";
+      sha256 = "/ADzScsG0u6RJbEtfO23Gup2NYdhPkExqqOPVcQa7aQ=";
+    };
+  };
+
 in
 {
   home.username = "${username}";
@@ -494,6 +505,7 @@ in
       vim-caser
       vim-heritage
       vim-just
+      vim-zoom
       vim-textobj-xmlattr
       vim-visual-star-search