Middy stores the request object on the global handler instance

[thetrevdev]

What are the steps to reproduce this issue?

This code shows the issue:
Calling a handler twice concurrently will clobber the request instance.

https://codesandbox.io/s/purple-star-n3ohc?file=/src/index.js

What happens?

The two requests clobber the instance object replacing both the context and responses.

What were you expecting to happen?

They are scoped and resolve independently

Any logs, error output, etc?

See example above.

What versions of software are you using?

Node.js Version: 10/12

Middy Version: 1.2.0

AWS SDK Version: 2x