Tidy neovim configuration

* Remove some unused plugins and packages.
  * e.g. floaterm, projectionist, vim-wiki, vim-easy-align,
    vim-surround, visual-star-search, vim-rhubarb
* Replace none-ls with conform.nvim and nvim-lint.
* Replace lualine.nvim with mini-statusline.
* Add neodev.
* Simplify cmp completion sources.

after/plugin/colorscheme.lua

@@ -8,6 +8,10 @@ catppuccin.setup {
   integrations = {
     cmp = true,
     gitsigns = true,
+    mini = {
+      enabled = true,
+      indentscope_color = "",
+    },
     native_lsp = {
       enabled = true,
     },