Support treemacs-ext with nerd-icons instead of all-the-icons

[tam5]

Describe your request

Somewhat recently doom dropped all-the-icons in favor of nerd-icons.

As part of that some of the extra visual tweaks present in doom-themes-ext-treemacs.el, like hiding the modeline for example, seem to have been lost.

What do ya'all think would be a recommended fix? Add a new extension for treemacs-with-nerd, split out treemacs-ext to separate icon handling from the rest, add additional conditional logic to existing treemacs-ext to just skip the all-the-icons stuff?

Briefly explain its use-case

Using doom with treemacs.

[sebastiaanspeck]

I do not know what the fix would be, but I have at least opened a PR to show the modeline again #824 since Alexander-Miller/treemacs#1049 made the modeline useful again

[Velnbur]

It's actually already done using treemacs-nerd-icons package by updating treemacs-load-theme to nerd-icons (see)