Nvim: switch to packer from Plug

.config/nvim/lua/core/temp.lua

@@ -2,14 +2,6 @@ require("virt-column").setup { }
 require('compiler-explorer').setup()
 require("symbols-outline").setup()
 
-require('pretty-fold').setup()
-require('pretty-fold').ft_setup('cpp', {
-   process_comment_signs = false,
-   --comment_signs = {
-   --   '//', -- C++ Doxygen comments
-   --},
-})
-require('fold-preview').setup()
 --require('lsp_lines').setup()
 
 require('image').setup {