Support protocol `init` requirements

[bradleymackey]

Is your feature request related to a problem? Please describe.
A spy is currently unable to be generated for init requirements. Any protocol with an init requirement will not synthesize correctly.

Describe the solution you'd like

protocol Thing {
  init(time: Double)
}

Should generate:

class ThingSpy: Thing {
  init() {}
  var initTimeReceivedTime: Double!
  required init(time: Double) {
    initTimeReceivedTime = time
  }
}

Describe alternatives you've considered
N/A

Additional context

• A default init without any parameters should still be generated.
• Only 1 value needs to be captured from the init requirements, because the object can only be created once.
• init protocol requirements must be prefixed with the required keyword.

[Boowman]

I 2nd this, had the same issue when I started using it.