[e2e framework] Extract assertions from set up

[chuckha]

User Story
Setting up a cluster is great, but we don't need to conflate all of the assertions with the actions of setting up.

Detailed Description
For example, a cluster should always come up. After that we want to make assertions about the cluster, but depending on the features the infrastructure provider supports they may or may not want to make certain assertions. One concrete example is FailureDomains. I'd like a way to assert that failure domains is working with my infrastructure provider, but since it's an optional feature, other infrastructure providers may not want to use those assertions.

/kind feature
/milestone Next
/priority important-longterm

[chuckha]

/assign
/active

[chuckha]

/lifecycle active