aws: add support for AWS CLI v2 autocompletion (#8670)

Co-authored-by: Marc Cornellà <marc.cornella@live.com>

plugins/aws/aws.plugin.zsh

@@ -62,6 +62,11 @@ fi
 
 # Load awscli completions
 
+# AWS CLI v2 comes with its own autocompletion. Check if that is there, otherwise fall back
+if [[ -x /usr/local/bin/aws_completer ]]; then
+  autoload -Uz bashcompinit && bashcompinit
+  complete -C aws_completer aws
+else
   function _awscli-homebrew-installed() {
     # check if Homebrew is installed
     (( $+commands[brew] )) || return 1
@@ -95,3 +100,4 @@ fi
 
   [[ -r $_aws_zsh_completer_path ]] && source $_aws_zsh_completer_path
   unset _aws_zsh_completer_path _brew_prefix
+fi