Fix named pipe in kubectl zsh completion

In zsh and bash, a multi-line named pipe, who is wrapped by
parenthesis, is possible to mismatch the right parenthesis, even that
parenthesis is in a here-document. So, we move the code into a
function, and use an inline named pipe.

Signed-off-by: ohmystack <jiangjun1990@gmail.com>

pkg/kubectl/cmd/completion.go

@@ -245,7 +245,8 @@ if sed --help 2>&1 | grep -q GNU; then
 	RWORD='\>'
 fi
 
-__kubectl_bash_source <(sed \
+__kubectl_convert_bash_to_zsh() {
+	sed \
 	-e 's/declare -F/whence -w/' \
 	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
 	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
@@ -267,7 +268,9 @@ __kubectl_bash_source <(sed \
 
 	zsh_tail := `
 BASH_COMPLETION_EOF
-)
+}
+
+__kubectl_bash_source <(__kubectl_convert_bash_to_zsh)
 `
 	out.Write([]byte(zsh_tail))
 	return nil