refactor(nvim): prefix custom Vim plugins

Prefix custom Vim plugins with `customVim` so they are easier to
distinguish from the plugins provided by the Nix store.

system/shared/home-manager.nix

@@ -1,6 +1,7 @@
 { inputs, pkgs, self, username }:
 
 let
+  customVim = with self; {
     vim-astro = pkgs.vimUtils.buildVimPlugin {
       name = "vim-astro";
       src = pkgs.fetchFromGitHub {
@@ -80,7 +81,7 @@ let
         sha256 = "/ADzScsG0u6RJbEtfO23Gup2NYdhPkExqqOPVcQa7aQ=";
       };
     };
-
+  };
 in
 {
   home.username = "${username}";
@@ -500,14 +501,14 @@ in
     enable = true;
 
     plugins = with pkgs; [
-      tabline-vim
+      customVim.tabline-vim
-      vim-astro
+      customVim.vim-astro
-      vim-caser
+      customVim.vim-caser
-      vim-heritage
+      customVim.vim-heritage
-      vim-just
+      customVim.vim-just
-      vim-zoom
+      customVim.vim-zoom
-      vim-textobj-xmlattr
+      customVim.vim-textobj-xmlattr
-      vim-visual-star-search
+      customVim.vim-visual-star-search
 
       vimPlugins.comment-nvim
       vimPlugins.dial-nvim