feat: Allow hiding mappings from the help panel

[fjchen7]

No description provided.

[sindrets]

@fjchen7 Thanks for the PR!

I'm missing some explanation for this change. What's the point of hiding entries from the help panel?

[fjchen7]

The final purpose is to make help panel cleaner if users want.

For me the specific requirement is:

require("diffview").setup {
  keymaps = {
    file_panel = {
      -- I don't want to show some conventional keymaps
      { "n", "j", actions.next_entry, { desc = false } },
      { "n", "<down>", actions.next_entry, { desc = false } },
      { "n", "k", actions.prev_entry, { desc = false } },
      { "n", "<up>", actions.prev_entry, { desc = false } },

      -- I want to disable some keymaps without showing them in the help panel.
      { "n", "<C-o>", "", { desc = false } },  -- Avoid accidentally messing up buffer
      { "n", "<C-i>", "", { desc = false } },
    }
  }
}

[sindrets]

Setting the desc field to anything other than a string is unintended usage of the nvim_set_keymap() API. While it seems to have no side effects right now; there's no guarantee it will stay that way in the future. We need to do this properly and special-case this behavior in the plugin's keymap processing.

You can check here whether the desc field has been set to false, and if so, change the value of the expanded mapping to __DIFFVIEW_IGNORED__ or something.

[fjchen7]

Of we directly choose the special string like __DIFFVIEW_IGNORED__ or something to hide keymap? (Just like which_key_ignore in which-key)

For example,

{ "n", "<2-LeftMouse>", actions.select_entry, { desc = "__DIFFVIEW_IGNORED__" } },

In my opinion, this could avoid conflict with the extension about desc = false in nvim_set_keymap() and may be better.

[sindrets]

@fjchen7 good call. Let's just go with "diffview_ignore" as the special value then.

[sindrets]

Thanks!