refactor(copydir)!: deprecate plugin in favor of `copypath`

BREAKING CHANGE: the `copydir` plugin is deprecated. Instead of
using `copydir`, use `copypath` which also supports copying
the path of other files or directories specified.

plugins/copydir/README.md

 # copydir plugin
 
-Copies the path of your current folder to the system clipboard.
-
-To use, add `copydir` to your plugins array:
-```
-plugins=(... copydir)
-```
-
-Then use the command `copydir` to copy the $PWD.
+This plugin is deprecated. Use the [`copypath` plugin](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/copypath) instead.

plugins/copydir/copydir.plugin.zsh

-# Copies the pathname of the current directory to the system or X Windows clipboard
+echo ${(%):-'%F{yellow}The `%Bcopydir%b` plugin is deprecated. Use the `%Bcopypath%b` plugin instead.%f'}
+source "$ZSH/plugins/copypath/copypath.plugin.zsh"
+
+# TODO: 2022-02-22: Remove deprecated copydir function.
 function copydir {
-  emulate -L zsh
-  print -n $PWD | clipcopy
+  copypath
 }