Add copilot chat and other nice things

lua/custom/plugins/copilot-chat.lua

@@ -0,0 +1,18 @@
+return {
+  {
+    'CopilotC-Nvim/CopilotChat.nvim',
+    dependencies = {
+      { 'nvim-lua/plenary.nvim', branch = 'master' },
+    },
+    build = 'make tiktoken',
+    init = function()
+      local map = vim.api.nvim_set_keymap
+      local opts = { noremap = true, silent = true }
+
+      map('n', '<leader>ch', '<Cmd>CopilotChatToggle<CR>', opts)
+    end,
+    opts = {
+      -- See Configuration section for options
+    },
+  },
+}