Allow to disable compinit

[outcoldman]

Implement ZGEN_AUTOLOAD_COMPINIT to allow disabling compinit in cases where you want to skip them for secure reasons. For example when you login as a root.

[outcoldman]

In my case I want to use something like

ZGEN_AUTOLOAD_COMPINIT=true
if [[ ${USER} == "root" ]]; then
    ZGEN_AUTOLOAD_COMPINIT=false
fi

so for root user I will not load autocomp. One of the reasons I don't want to see this error

zsh compinit: insecure directories, run compaudit for list.
Ignore insecure directories and continue [y] or abort compinit [n]?

[tarjoilija]

Thank you!