gossipsub: add test for missed heartbeats

[thomaseizinger]

We should have a test that ensure we "catch" up to missed heartbeats. For the underlying timer, this means implementing a "skip" behavior.

The test should be on a Swarm level ideally such that we don't rely on implementation details.

The cherry on the cake would be to run the test in wasm as well to make sure the timer implementation is always sane.

Originally discussed in #3973 (comment)

[dgarus]

@thomaseizinger
Hi!
I'd like to take this issue, WDYT?

[thomaseizinger]

It might be worth waiting for #4015 to be merged because it introduces WASM testing in CI.

[thomaseizinger]

I started a discussion here because it is not clear to me what the best approach regarding wasm tests is.