Emit a Keep alive / Time out error

[RobinCPel]

Our team is currently using this library, and we would love it if we were able to log time-out issues. This PR makes it possible! ❤️

Note: When the WS connection times out, it has to be force closed when reconnect is not enabled, otherwise, checkConnectionIntervalId will keep on spewing out timed-out errors... forever. I don't know if this has any bad side effects? The tests still seem to pass just fine! ^^

TODO:

• [x] Make sure all of the significant new logic is covered by tests
• [x] Rebase your changes on master so that they can be merged easily
• [x] Make sure all tests and linter rules pass
• [x] Update CHANGELOG.md with your change

[apollo-cla]

@RobinCPel: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[RobinCPel]

Nvm, we fixed it by implementing this library.

[glasser]

Good to hear. We are in the process of ensuring that everything in the Apollo platform supports the library you've found so that we can fully archive this project.