Move exports for more modules

[pakrym-stripe]

Moves the rest of public modules to private and adds compatibility shims.

oauth_errors is the only module that I kept as is. Types from it conflict with standard error types.

Changelog

• stripe.app_info, stripe.http_client, stripe.oauth, stripe.util, stripe.version, stripe.webhook, modules are deprecated. All types are available directly from stripe module now.
  Before:

  from stripe.util import convert_to_stripe_object
  # or
  stripe.util.convert_to_stripe_object

  After:

  from stripe import convert_to_stripe_object
  # or
  stripe.convert_to_stripe_object

• stripe.api_version, stripe.multipart_data_generator, stripe.request_metrics are deprecated and will be fully removed in the future.

[anniel-stripe]

LGTM!

oauth_errors is the only module that I kept as is. Types from it conflict with standard error types.

Do we have a plan to make this module private in the future?