feat(chunk): better textobject-keymap

[zerachiel016]

What does this PR do ?

• Only set the chunk-textobject-keymap Localy to allowed-filetypes buffers so it doesn't conflict for instance with other keymaps in non-concerned/excluded buffers
• Add a keymap description to the textobject-keymap, useful for which-key users or other... so now you can set it up like this:

textobject = {
      keymap = "ic",
      desc = "inner chunk",
  },

What's missing ?

Need someone to update the chinese docs :'/