Sets expiry of token generated using refresh_token to that of original token [Fixes #1364]

[rishabhsairawat]

This PR aims to fix #1364 .

See the following example:

Doorkeeper Configuration

Doorkeeper.configure do
  # ...
  access_token_expires_in 3.hours

  custom_access_token_expires_in do |context|
     if context.grant_type == Doorkeeper::OAuth::PASSWORD
        1.hour
     elsif context.grant_type == Doorkeeper::OAuth::AUTHORIZATION_CODE
        2.hours
     end

  end

  use_refresh_token do |context|
     true
  end
  
# ...
end

Behavior without this fix:

• When refreshing a token(originally created using authorization_code flow having the expiry of 2 hours), the new token will have an expiry of 3 hours.

• When refreshing a token(originally created using password flow having the expiry of 1 hour), the new token will have an expiry of 3 hours.

Behavior after this fix:

• When refreshing a token(originally created using authorization_code flow having the expiry of 2 hours), the new token will also have an expiry of 2 hours.

• When refreshing a token(originally created using password flow having the expiry of 1 hour), the new token will also have an expiry of 1 hour.

[nbulaj]

🚝

thanks @rishabhsairawat !