Add theme settings for lsp's headerline icons

[Velnbur]

I really in love with this theme, and it's built-in capabilites for treemacs, but also I'm missing suitable icons for lsp's breadcrumbs.

I have a little bit of expirience in this (see), so can commit on implementing it

[Velnbur]

Works for me as a Rust developer. But for other languages this should be tested out. I'm also not sure about specific icons usage, as firstly I thought that all-the-icons (like the nerd-icons) has icons from VS Code breadcrumbs, but that wasn't true, so I tried to improvise.

(use-package kaolin-themes
  :config
  (load-theme 'kaolin-dark t)
  (with-eval-after-load 'lsp-treemacs
    (with-eval-after-load 'treemacs

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "functions" :height 0.8 :v-adjust 0.05))
       :extensions (method function))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "class"))
       :extensions ("class"))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "book"))
       :extensions (project))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-octicon "package"))
       :extensions (package))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-octicon "file-code"))
       :extensions (document))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "label" :height 0.8))
       :extensions (field property))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "tags" :height 0.8 :v-adjust 0.05))
       :extensions (constant))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-octicon "code" :v-adjust 0.055 :height 0.9))
       :extensions (namespace))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "cube" :v-adjust 0.055 :height 0.9))
       :extensions (interface))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "featured_play_list" :height 0.8))
       :extensions (structure))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-material "text_fields" :height 0.8))
       :extensions (string))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "check-square-o" :height 0.8 :v-adjust 0.05))
       :extensions (boolean-data))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "sliders"  :height 0.8 :v-adjust 0.07))
       :extensions (numeric))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "cubes" :height 0.8 :v-adjust 0.05))
       :extensions (enumerator enum))

      (treemacs-create-icon
       :icon (format "%s" (all-the-icons-faicon "cube" :height 0.8 :v-adjust 0.05))
       :extensions (enumMember enum-member enumitem))
      
      (kaolin-treemacs-theme)
      (setq lsp-treemacs-theme "kaolin"))))