feat(config): Change custom icons to columns config

lua/oil/config.lua

@@ -2,7 +2,7 @@ local default_config = {
   -- Id is automatically added at the beginning, and name at the end
   -- See :help oil-columns
   columns = {
-    "icon",
+    { "icon", default_file = "", directory = " " },
     -- "permissions",
     -- "size",
     -- "mtime",
@@ -22,11 +22,6 @@ local default_config = {
     conceallevel = 3,
     concealcursor = "n",
   },
-  -- Custom icons
-  icons = {
-    default_file = "",
-    directory = " ",
-  },
   -- Oil will take over directory buffers (e.g. `vim .` or `:e src/`
   default_file_explorer = true,
   -- Restore window options to previous values when leaving an oil buffer