refactor(rbfu)!: remove deprecated `rbfu` plugin

BREAKING CHANGE: `rbfu`, the tool to manage Ruby versions, has long
been deprecated (2013-02-05). The plugin has been removed. If you
were still using it, consider using alternative Ruby version
managers: https://www.jetbrains.com/help/ruby/ruby-version-managers.html

plugins/rbfu/README.md

@@ -1,18 +0,0 @@
-# rbfu plugin
-
-This plugin starts [rbfu](https://github.com/hmans/rbfu), a minimal Ruby version
-manager, and adds some useful functions.
-
-To use it, add `rbfu` to the plugins array in your zshrc file:
-
-```zsh
-plugins=(... rbfu)
-```
-
-**Note: `rbfu` is deprecated and should no longer be used.**
-
-## Functions
-
-- `rbfu-rubies`: lists all installed rubies available to rbfu.
-
-- `rvm_prompt_info`: shows the Ruby version being used with rbfu.

plugins/rbfu/rbfu.plugin.zsh

@@ -1,49 +0,0 @@
-# Enables rbfu with --auto option, if available.
-#
-# Also provides a command to list all installed/available
-# rubies. To ensure compatibility with themes, creates the
-# rvm_prompt_info function to return the $RBFU_RUBY_VERSION
-# version.
-
-command -v rbfu &>/dev/null || return
-
-eval "$(rbfu --init --auto)"
-
-# Internal: Print ruby version details, if it's currently active, etc.
-function _rbfu_rubies_print() {
-  # 1: path to ruby file
-  # 2: active ruby
-  local rb rb_out
-  rb="${$1:t}"
-  rb_out="$rb"
-
-  # If the ruby is a symlink, add @ to the name.
-  if [[ -h "$1" ]]; then
-    rb_out="${rb_out}${fg[green]}@${reset_color}"
-  fi
-
-  # If the ruby is active, add * to the name and show it in red.
-  if [[ "$rb" = "$2" ]]; then
-    rb_out="${fg[red]}${rb_out} ${fg[red]}*${reset_color}"
-  fi
-
-  echo $rb_out
-}
-
-# Public: Provide a list with all available rubies, this basically depends
-# on ~/.rfbu/rubies. Highlights the currently active ruby version and aliases.
-function rbfu-rubies() {
-  local rbfu_dir active_rb
-  rbfu_dir="${RBFU_RUBIES:-${HOME}/.rbfu/rubies}"
-  active_rb="${RBFU_RUBY_VERSION:-system}"
-
-  _rbfu_rubies_print "${rbfu_dir}/system" "$active_rb"
-  for rb in ${rbfu_dir}/*(N); do
-    _rbfu_rubies_print "$rb" "$active_rb"
-  done
-}
-
-# Public: Create rvm_prompt_info command for themes compatibility, unless
-# it has already been defined.
-(( ${+functions[rvm_prompt_info]} )) || \
-function rvm_prompt_info() { echo "${${RBFU_RUBY_VERSION:=system}:gs/%/%%}" }