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/mini.lua

@@ -0,0 +1,22 @@
+require("mini.ai").setup {}
+
+require("mini.align").setup {}
+
+require("mini.bracketed").setup {}
+
+require("mini.hipatterns").setup {
+  highlighters = {
+    note = { pattern = "%f[%w]()NOTE()%f[%W]", group = "MiniHipatternsNote" },
+    todo = { pattern = "%f[%w]()TODO()%f[%W]", group = "MiniHipatternsTodo" },
+  },
+}
+
+require("mini.move").setup {}
+
+require("mini.operators").setup {}
+
+require("mini.splitjoin").setup {}
+
+require("mini.statusline").setup {}
+
+require("mini.surround").setup {}