Automatic updates#622

TLDR:
I would really like to see the admin worload reduced with automatic updates. I think Kirby should automatically non-breaking updates, especially security patches.

More details:
Obviously, some updates will require testing to ensure they don’t break a site and those should not auto-install. However, having to manually install every single update is a major reason I am regularly considering using a different CMS for client projects. With every additional project, the admin-workload increases, and I think some updates should install themselves without asking.

Some Suggestions:

• I would appreciate if auto-installs sent an email to the admin before installing and when done. This way I see an update started but failed to finish, for example. Every Kirby install could do this autonomously.
• Updates that can not auto-install, should send an email to the admin. Every Kirby install could do this autonomously.
• Enabling/disabling auto-updates should be possible in the panel, but only for admins.
• When an auto-update fails, the site should “lock”, as in it should be static, with the panel in admin-only mode, and the current version of the public website being served from cache until the issue is resolved. The site should not go down. I understand this makes the whole thing a ton more complicated, but maybe it could be a feature added at a later date, after auto-updated have already been implemented and shipped.