Simplify cloning in the UI by leaving only one button

It's difficult to remember what's difference between Clone and Full clone. And now, when template nesting is removed, it's even more difficult to explain why does Clone copies tags and value maps but doesn't copy items in templates.

Zabbix should at least remove the Clone button in Templates (leaving only Full clone), but ideally, every form should have only one Clone button, which does exactly Clone - i.e. creates a carbon copy of the entity.