Add `bin/spring stop` default before hook for gdk stop/update

What does this Merge Request do?

This MR adds a default cd gitlab && bin/spring stop before hook for gdk stop/update.

gdk stop

gdk.yml

gdk:
  stop_hooks:
    before:
      - "uptime"
      - "date"

$ gdk config get gdk.stop_hooks.before
cd gitlab && bin/spring stop
uptime
date

gdk update

No gdk.yml

$ gdk config get gdk.update_hooks.before
cd gitlab && bin/spring stop

Closes: #852 (closed)

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.