Envoy: Support level trigger user space event and resolve `fails_on_windows` introduced in #13418

[lambdai]

@lambdai if you leave fails_on_windows tests do you mind opening an issue and tagging it as windows only with some context on the feature that we need to implement. We do this because it is easier to track than fails_on_windows tags.

@davinci26
Absolutely. I will add immediately after the PR is merged.

_Originally posted by @lambdai in https://github.com/envoyproxy/envoy/pull/13418#issuecomment-718886166_

[sunjayBhatia]

@lambdai could you add some more detail about why the test is marked as failing and how the test fails? (error output, failed expectations, etc.)

[lambdai]

@sunjayBhatia I can add more details or fixed it when the PR is landed.

Basically I am creating a user space event implementation. And the implementation in that PR only support edge trigger.

It's an ASSERT failure "level trigger type" is passed in.

My entire PR is an extension so it's completely safe if you don't enable it.

[davinci26]

I think I can get this "for free" with #13787 feel free to assign this to me

[sunjayBhatia]

/assign davinci26