Follows up #968.
As a relic from when we had global configuration, anytime any config
value is changed on any client, we still clear all connection managers
everywhere on every thread, even though this is not necessary. This
means that we lose all open connections, etc.
Here, we make changes so that if a configuration is changed, we only
clear the configuration managers pertaining to that one particular
configuration, thus conserving resources globally.
Co-authored-by: Brandur <brandur@brandur.org>
This changes allows for each instance of StripeClient to have its own
configuration object instead of relying on the global config. Each
instance can be configured to override any global config values
previously set.
Adds a `Stripe::StripeConfiguration` object to manage internal and user
supplied configuration options.
This is primarily motivated by #921 in order to provide a way to set
options on for an instance of `StripeClient`.
