Merge and codegen from master stripe-ruby v13.0.0

[helenye-stripe]

Why?

This is the merge from master after v13.0.0. It removes Preview from beta as well in favor of raw request.

• Added deprecation warnings in stripe.rb

I also codegenned as part of this, but shouldn't cause any issues.

Changelog

• Remove Stripe::Preview. Use StripeClient#raw_request instead (see below).

• Marked Stripe.raw_request and Stripe.deserialize as deprecated. Use StripeClient#raw_request and StripeClient#deserialize instead. In StripeClient, the params and opts parameters are passed as keyword arguments:

  # Before
  resp = Stripe.raw_request(:post, "v1/charges", , {p1: "p1"}, {stripe_account: "acct_123"})
  charge = Stripe.deserialize(resp.data)
  
  # After
  client = StripeClient.new("sk_test_123") 
  resp = client.raw_request(:post, "/v1/charges", params: {p1: "p1"}, opts: {stripe_account: "acct_123"})
  charge = client.deserialize(resp.data)