Implement exponential retry/backoff mechanism in k8s pod exec

Hey there!

We've internally been experiencing issues with the following two issues:

In this PR I attempted to tackle them both by;

Making sure the await from exec.exec is wrapped in a try/catch so UnhandledPromiseRejection errors should no longer occur to this
I've wrapped the call to k8s.Exec.exec() in an exponential backoff using this package. This should mitigate the rare HttpErrors sometimes being thrown from this function.

Typescript is not my main language so apologies if things are not entirely how they should be, did my best to add some proper tests for it 💪

Please please don't hesitate to make (major) edits to this PR! I'd be very happy if that would close these issues quicker 😄

Thanks!

actions / runner-container-hooks