Add a NimbleOperatorRule

[marcelofabri]

We use Nimble on our unit tests, and we prefer using its operator overloads instead of functions:

// triggers
expect(seagull.squawk).toNot(equal("Hi"))
expect(10).to(beGreaterThan(2))

// doesn't trigger
expect(seagull.squawk) != "Hi!"
expect(10) > 2

Creating a rule to enforce this shouldn't be too hard. However, even if it's opt-in I know it's a very specific use case. Would this be a welcome rule addition?

[wongzigii]

@marcelofabri

Linting Nimble's library code with comma rule will result in :

// before
expect([1,2,3,4]).to(allPass({$0 < 5}))

// after
expect([1, 2,3, 4]).to(allPass({$0 < 5}))

Is this an expected behavior?

[marcelofabri]

I'm not sure how this is related to this issue, but it seems it's a consequence of #872 with autocorrect.