nvim: Change remaining augroups to lua autocmds

Changed formatting and plugin self-compilation to make use of the new
neovim 0.7 autcmd api function.

nvim/.config/nvim/lua/plug/_format.lua

@@ -54,9 +54,12 @@ local formatters = {
 
 require('formatter').setup({logging = false, filetype = formatters})
 
+-- Format on save:
 -- gather filetypes to autocorrect for each activated formatter above
-local filetype = ""
-for k, _ in pairs(formatters) do filetype = filetype .. "," .. k end
-augroup({
-    {'FileType', filetype, 'autocmd', 'BufWritePost', '<buffer>', 'FormatWrite'}
-}, 'formatonsave')
+for k, _ in pairs(formatters) do
+    vim.api.nvim_create_autocmd({"Filetype " .. k}, {
+        command = "autocmd BufWritePost <buffer> FormatWrite",
+        desc = "Automatically format on write",
+        group = vim.api.nvim_create_augroup('formatonsave', {clear = true})
+    })
+end

nvim/.config/nvim/lua/plugins.lua

@@ -2,15 +2,16 @@ local install_path = vim.fn.stdpath("data") .. "/pack/packer/start/packer.nvim"
 
 if vim.fn.empty(vim.fn.glob(install_path)) > 0 then
     vim.cmd("!git clone https://github.com/wbthomason/packer.nvim " ..
-                install_path)
+        install_path)
 end
 
-vim.api.nvim_exec([[
-  augroup Packer
-    autocmd!
-    autocmd BufWritePost plugins.lua PackerCompile
-  augroup END
-]], false)
+-- Compile on plugin edits
+vim.api.nvim_create_autocmd({ "BufWritePost" }, {
+    pattern = "plugins.lua",
+    command = "PackerCompile",
+    desc = "Compile plugins after editing plugin list",
+    group = vim.api.nvim_create_augroup('compilepackages', { clear = true })
+})
 
 local use = require("packer").use
 require("packer").startup(function()