Refactor neovim config (#2)

Changes include:

- [x] Use init.lua instead of init.vim
   - Some keybindings are still to be converted
- [x] Use packer as a package manager instead of vim-plug
- [ ] Use built-in lsp instead of coc.nvim
   - [x] Set up language servers
   - [x] Completion
   - [x] Formatting (previously coc-prettier, now neoformat)
   - [ ] Snippets
- [ ] Replace fzf with telescope.nvim
- [x] Implement treesitter syntax highlighting
   - More info: https://github.com/nvim-treesitter/nvim-treesitter

Note that this requires neovim nightly until 0.5 is released

Reviewed-on: #2
Co-authored-by: Marko Korhonen <marko@korhonen.cc>
Co-committed-by: Marko Korhonen <marko@korhonen.cc>

home/.config/zsh/03-aliases.zsh

@@ -149,7 +149,7 @@ update() {
 	}
 
 	plugins() {
-		vim +PlugUpgrade +PlugUpdate +CocUpdate +qa
+		nvim +PackerUpdate +TSUpdate +qa
 		zinit self-update
 		zinit update -p
 		$HOME/.tmux/plugins/tpm/bin/update_plugins all