Pass params to transfer reversal

[prathmesh-stripe]

Related: #1393

Changelog

• Allow Stripe::Transfer.retrieve_reversal() to accept a params hash as the third argument, followed by opts. No changes to existing calls are necessary, but in a future major version this method will be updated to only accept params as the first argument.

[helenye-stripe]

accept a params hash as the first argument

I think this should be the third argument?

Also would you mind also adding a generic test to

stripe-ruby/test/stripe/api_operations_test.rb

Line 66 in f538d42

context ".nested_resource_class_methods" do

?

[helenye-stripe]

thanks for this!