[zsh completion] Expand aliases recursively

[sei40kr]

Description

What this PR does:

• Expand aliases recursively to find a proper completer

e.g.

$ alias s=ssh

$ s ** # press tab here to complete hostnames

[NemesisRE]

I just started to work with kubectl for some time. The default alias everyone suggesting is k which is convenient cause the rest of the commands can get pretty long. If that pr works as expect it would make things so much easier.