Provide :touch option to save() to accommodate saving without updating t...

...imestamps. [#18202]
I like this, although the addition of keyword arguments to the method signature will require handling `:validate` as well. Additionally, we have to account for a possible positional argument, namely [an array of model attributes](https://github.com/rails/rails/blob/master/activerecord/lib/active_record/locking/optimistic.rb#L69).

The adjusted method signature would read as:

```ruby
def _update_record(*args, touch: true, validate: true)
```

WDYT?