Warn if opts are in params

[vcheung-stripe]

Summary

Warn the user if they mistakenly put options into the $params argument to a method, similar to the Stripe Node warning. For example, we warn when the user includes an api_key in $params.

Motivation

https://jira.corp.stripe.com/browse/DX-6065

Testing

Unit tests

[vcheung-stripe]

First time writing PHP, so not sure if I'm following the right conventions or even putting code in the write place. Would love nitpicks.

[richardm-stripe]

Fantastic!

[richardm-stripe]

Since you asked for nits: sometimes I prefer a foreach vs. \array_filter in PHP when I would do the opposite in e.g. Javascript because lambdas have a heavy syntax. I also lean towards variable interpolation rather than \sprintf, but there are precedents for both \array_filter and \sprintf already in stripe-php and would not necessarily change what you have.

[vcheung-stripe]

Since you asked for nits: sometimes I prefer a foreach vs. \array_filter in PHP when I would do the opposite in e.g. Javascript because lambdas have a heavy syntax. I also lean towards variable interpolation rather than \sprintf, but there are precedents for both \array_filter and \sprintf already in stripe-php and would not necessarily change what you have.

Will keep what I have, but good to know.