feat(builtins): Load new built-in plugins in >0.12

nvim-0.12 brings a native undotree plugin which I am going to experiment
with.
And a nohlsearch plugin that triggers nohlsearch after 4 seconds has
passed without a searching action, this is just neat.

lua/plugins/spec/builtin.lua

@@ -0,0 +1,26 @@
+---@module 'lazy'
+---@type LazySpec
+return{
+	{
+		name = 'nohlsearch',
+		virtual = true,
+		dir = 'nohlsearch',
+		enabled = function ()
+			return vim.fn.has('nvim-0.12') == 1
+		end,
+		init = function()
+			vim.cmd([[packadd nohlsearch]])
+		end
+	},
+	{
+		name = 'nvim.undotree',
+		virtual = true,
+		dir = 'nvim.undotree',
+		enabled = function ()
+			return vim.fn.has('nvim-0.12') == 1
+		end,
+		init = function()
+			vim.cmd([[packadd nvim.undotree]])
+		end
+	}
+}