Patch for async-http

[ScotterC]

Describe the idea
Sentry comes bundled with getting performance spans for Net::Http and a patch for Faraday is easy to enable. Are there any plans for an async-http? Ruby async is now built into ruby and is becoming much more common place for concurrent IO operations like external API requests.

Why do you think it's beneficial to most of the users
When understanding performance issues, external http calls can be a big hit. Currently if using async-http these show up as "Missing Instrumentation" in Sentry. Also, when improving IO performance, moving calls to asynchronous calls is a common tool applied which one would want to see reflected in Sentry perf dashboards.

Possible implementation

• A workaround might be using async-http-faraday
• It may follow similar lines as https://github.com/getsentry/sentry-ruby/blob/master/sentry-ruby/lib/sentry/faraday.rb