fix(yarn): use `builtin cd` in yarn completion

[hwknsj]

fix(yarn): use builtin cd in yarn completion to avoid infinite loop

This is a clone of my pull request on the oh-my-zsh repository which has been merged into production branch.

This simply replaces 3 instances of cd in the _yarn completion script with builtin cd to avoid issues in the case that cd has been aliased or redefined. While this may sound like an unusual situation, consider the example below.

Example: cd is 'enhanced' to list contents of the new directory, e.g.

function cd () {
    builtin cd "$1"
    ls -laFhGT
}

Chaos ensues on invoking completion, yarn ⇥ tab

Here is a video screen recording if asciinema link goes away:

Standards checklist:

• [x] The PR title is descriptive.
• [x] The PR doesn't replicate another PR which is already open.
• [x] I have read the contribution guide and followed all the instructions.
• [x] The code follows the code style guide detailed in the wiki.
• [x] The code is mine or it's from somewhere with an MIT-compatible license.
• [x] The code is efficient, to the best of my ability, and does not waste computer resources.
• [x] The code is stable and I have tested it myself, to the best of my abilities.
• [ ] If the code introduces new aliases, I provide a valid use case for all plugin users down below.

Changes:

• replaced 3 instances of cd with builtin cd in _yarn compdef
• specifies UTF-8 binmode in perl script that parses package.json scripts: {} object key:values (aligns with completion in ohmyzsh yarn plugin)

Other comments:

I can't really think of a better way to do this. I considered /bin/cd, but we can pretty safely assume that the user's shell is zsh and builtin cd always works.

[syohex]

Thanks