Make `doom/increase-font-size` to adjust more fonts

I sometimes type Korean characters in Emacs, and I have set the font like below.
```elisp
(set-fontset-font t 'hangul (font-spec :family "NotoSans CJK KR" :size 15))
```
However, if I try to adjust the size of the fonts with `doom/increase-font-size`,
it does not change the size of `hangul` fonts that I have manually set.

It would be nice if there is a unified interface for controlling the font size.

FWIW, currently it does not change the font size of `treemacs` buffer, either.

**System information**

((system

  (type . gnu/linux)

  (config . "x86_64-pc-linux-gnu")

  (shell . "/usr/bin/zsh")

  (uname . "Linux 5.9.2-arch1-1 #1 SMP PREEMPT Thu, 29 Oct 2020 17:01:28 +0000 x86_64")

  (path "~/.opam/default/bin" "~/.cabal/bin" "~/.ghcup/bin" "~/.nix-profile/bin" "~/go/bin" "~/src/chromium/depot_tools" "/opt/cuda/bin" "~/.autojump/bin" "~/.local/bin" "~/.cargo/bin" "~/.cargo/bin" "/sbin" "/bin" "/usr/local/sbin" "/usr/local/bin" "/usr/bin" "/usr/sbin" "/opt/cuda/bin" "/usr/lib/jvm/default/bin" "/usr/bin/site_perl" "/usr/bin/vendor_perl" "/usr/bin/core_perl" "~/.gem/ruby/2.7.0/bin" "/usr/lib/emacs/28.0.50/x86_64-pc-linux-gnu"))

 (emacs

  (dir . "~/.emacs.d/")

  (version . "28.0.50")

  (build . "Oct 16, 2020")

  (buildopts . "--prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games --with-sound=alsa --with-modules --without-gconf --without-gsettings --with-x-toolkit=gtk3 --without-xaw3d --without-compress-install 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -flto -flto' CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now")

  (features . "XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GLIB NOTIFY INOTIFY ACL GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON PDUMPER LCMS2")

  (traits batch server-running envvar-file))

 (doom

  (dir . "~/.dotfiles/.doom.d/")

  (version . "2.0.9")

  (build . "HEAD -> develop, origin/develop, origin/HEAD 2e476de44 2020-10-16 00:28:25 -0400")

  (elc-files . 0)

  (modules :completion company (ivy +swiper) :ui deft doom doom-dashboard doom-quit fill-column hl-todo modeline ophints (popup +defaults) treemacs vc-gutter vi-tilde-fringe workspaces :editor (evil +everywhere) file-templates fold snippets :emacs (dired +icons +ranger) electric undo vc :term vterm :checkers syntax spell :tools docker (eval +overlay) lookup (lsp +peek +lsp-ui) magit pdf tmux :lang (cc +lsp) coq csharp emacs-lisp fsharp fstar (go +lsp) (haskell +lsp) latex markdown nix (org +roam) (python +lsp) racket rst (rust +lsp) sh yaml :config (default +bindings +smartparens))

  (packages (dracula-theme) (org-ref))

  (unpin "n/a")

  (elpa "n/a")))