Create module `get-time`

[RiftLurker]

The module should return the current screeps time, this basically comes down to creating a function that returns Game.time.

Benefit of using this module is the separation of concern, if the screeps api were to ever change we can just update this module and everything is sorted.

The following modules should be created alongside this one:

• [ ] is-past - isPast(time)
• [ ] is-present - isPresent(time)
• [ ] is-future - isFuture(time)