Currently `ActiveSupport::Duration` implicitly converts to a seconds
value when used in a calculation except for the explicit examples of
addition and subtraction where the duration is the receiver, e.g:
>> 2 * 1.day
=> 172800
This results in lots of confusion especially when using durations
with dates because adding/subtracting a value from a date treats
integers as a day and not a second, e.g:
>> Date.today
=> Wed, 01 Mar 2017
>> Date.today + 2 * 1.day
=> Mon, 10 Apr 2490
To fix this we're implementing `coerce` so that we can provide a
deprecation warning with the intent of removing the implicit coercion
in Rails 5.2, e.g:
>> 2 * 1.day
DEPRECATION WARNING: Implicit coercion of ActiveSupport::Duration
to a Numeric is deprecated and will raise a TypeError in Rails 5.2.
=> 172800
In Rails 5.2 it will raise `TypeError`, e.g:
>> 2 * 1.day
TypeError: ActiveSupport::Duration can't be coerced into Integer
This is the same behavior as with other types in Ruby, e.g:
>> 2 * "foo"
TypeError: String can't be coerced into Integer
>> "foo" * 2
=> "foofoo"
As part of this deprecation add `*` and `/` methods to `AS::Duration`
so that calculations that keep the duration as the receiver work
correctly whether the final receiver is a `Date` or `Time`, e.g:
>> Date.today
=> Wed, 01 Mar 2017
>> Date.today + 1.day * 2
=> Fri, 03 Mar 2017
Fixes#27457.
75924c4517