plugins/lazy.nvim: new plugin manager (#1175)

tests/test-sources/plugins/pluginmanagers/lazy.nix

@@ -0,0 +1,72 @@
+{pkgs, ...}: {
+  # Empty configuration
+  empty = {
+    plugins.lazy.enable = true;
+  };
+
+  test = {
+    plugins.lazy = with pkgs.vimPlugins; {
+      enable = true;
+
+      plugins = [
+        vim-closer
+
+        # Load on specific commands
+        {
+          pkg = vim-dispatch;
+          optional = true;
+          cmd = ["Dispatch" "Make" "Focus" "Start"];
+        }
+
+        # Load on an autocommand event
+        {
+          pkg = vim-matchup;
+          event = "VimEnter";
+        }
+
+        # Load on a combination of conditions: specific filetypes or commands
+        {
+          pkg = ale;
+          name = "w0rp/ale";
+          ft = ["sh" "zsh" "bash" "c" "cpp" "cmake" "html" "markdown" "racket" "vim" "tex"];
+          cmd = "ALEEnable";
+        }
+
+        # Plugins can have dependencies on other plugins
+        {
+          pkg = completion-nvim;
+          optional = true;
+          dependencies = [
+            {
+              pkg = vim-vsnip;
+              optional = true;
+            }
+            {
+              pkg = vim-vsnip-integ;
+              optional = true;
+            }
+          ];
+        }
+
+        # Plugins can have post-install/update hooks
+        {
+          pkg = markdown-preview-nvim;
+          cmd = "MarkdownPreview";
+        }
+
+        # Post-install/update hook with neovim command
+        {
+          pkg = nvim-treesitter;
+          opts = {ensure_installed = {};};
+        }
+
+        # Use dependency and run lua function after load
+        {
+          pkg = gitsigns-nvim;
+          dependencies = [plenary-nvim];
+          config = ''function() require("gitsigns").setup() end'';
+        }
+      ];
+    };
+  };
+}