refactor!: remove deprecated plugins

BREAKING CHANGE: the following deprecated plugins have been removed:
`cargo`, `copydir`, `npx`, `osx`, and `rustup`. See the wiki for more info:
https://github.com/ohmyzsh/ohmyzsh/wiki/Plugins#removed

refactor(rustup)!: remove deprecated plugin

BREAKING CHANGE: the plugin was deprecated and is now removed. See the wiki for more info:
https://github.com/ohmyzsh/ohmyzsh/wiki/Plugins#removed

plugins/cargo/README.md

-# cargo
-
-**Deprecated: use the [`rust`](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/rust) plugin instead.**

plugins/cargo/cargo.plugin.zsh

-print ${(%):-'%F{yellow}The `cargo` plugin is deprecated and has been moved to the `rust` plugin.'}
-print ${(%):-'Please update your .zshrc to use the `%Brust%b` plugin instead.%f'}
-
-(( ${fpath[(Ie)$ZSH/plugins/rust]} )) || {
-  fpath=("$ZSH/plugins/rust" $fpath)
-  source "$ZSH/plugins/rust/rust.plugin.zsh"
-}

plugins/copydir/README.md

-# copydir plugin
-
-This plugin is deprecated. Use the [`copypath` plugin](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/copypath) instead.

plugins/copydir/copydir.plugin.zsh

-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 {
-  copypath
-}

plugins/npx/README.md

-# npx plugin
-
-## Deprecation
-
-Since npm v7, `npx` has been moved to `npm exec`. With the move, [the `--shell-auto-fallback` argument
-for `npx` has been removed](https://github.com/npm/cli/blob/v7.0.0/docs/content/cli-commands/npm-exec.md#compatibility-with-older-npx-versions):
-
-> Shell fallback functionality is removed, as it is not advisable.
-
-When using npm v7, you'll get this error:
-
-> npx: the --shell-auto-fallback argument has been removed
-
-If you get this error, just disable the plugin by removing it from the plugins array in your zshrc file.
-This plugin will no longer be maintained and will be removed in the future, when the older `npx` versions
-are no longer available.

plugins/npx/npx.plugin.zsh

-if (( ! $+commands[npx] )); then
-  return
-fi
-
-if ! npx_fallback_script="$(npx --shell-auto-fallback zsh 2>/dev/null)"; then
-  print -u2 ${(%):-"%F{yellow}This \`npx\` version ($(npx --version)) is not supported.%f"}
-else
-  source <(<<< "$npx_fallback_script")
-fi
-
-print -u2 ${(%):-"%F{yellow}The \`npx\` plugin is deprecated and will be removed soon. %BPlease disable it%b.%f"}
-unset npx_fallback_script

plugins/osx/README.md

-# osx plugin
-
-**Deprecated: use the [`macos`](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/macos) plugin instead.**

plugins/osx/osx.plugin.zsh

-print -u2 ${(%):-'%F{yellow}The `osx` plugin is deprecated and has been renamed to `macos`.'}
-print -u2 ${(%):-'Please update your .zshrc to use the `%Bmacos%b` plugin instead.%f'}
-
-(( ${fpath[(Ie)$ZSH/plugins/macos]} )) || fpath=("$ZSH/plugins/macos" $fpath)
-source "$ZSH/plugins/macos/macos.plugin.zsh"

plugins/rustup/README.md

-# rustup
-
-**Deprecated: use the [`rust`](https://github.com/ohmyzsh/ohmyzsh/tree/master/plugins/rust) plugin instead.**

plugins/rustup/rustup.plugin.zsh

-print ${(%):-'%F{yellow}The `rustup` plugin is deprecated and has been moved to the `rust` plugin.'}
-print ${(%):-'Please update your .zshrc to use the `%Brust%b` plugin instead.%f'}
-
-(( ${fpath[(Ie)$ZSH/plugins/rust]} )) || {
-  fpath=("$ZSH/plugins/rust" $fpath)
-  source "$ZSH/plugins/rust/rust.plugin.zsh"
-}