Early codegen fixes

[ob-stripe]

r? @remi-stripe @marko-stripe
cc @stripe/api-libraries

A bunch of fixes I pulled from @marko-stripe's almost-ready codegen branch:

• fix a lot of PHPDoc blocks
• use $opts instead of $options everywhere
• standardize all but one methods to accept $params and $opts
  • the only exception is Dispute.close() which already accepts $opts, so adding $params first would be a breaking change. I left a TODO so we can fix in the next major version