Allow the use of all Rollables in Dice

[Samasaur1]

Is your feature request related to a problem? Please describe.

It doesn't make a lot of sense that WeightedDie cannot be used in Dice, and in a larger sense why any Rollable can't be. Rollable requires implementations of what I'm pretty sure are all the rolling/probabilities methods that Die has that Dice uses. It requires looking into, and refactoring some parts of Dice, but it seems like an overdue feature.

Describe the solution you'd like:

Users should be able to use and Rollable type in Dice. This includes the initializers (probably excluding the dice notation String-based initializer), operators, and pretty much everywhere else.

Describe alternatives you've considered:

Maybe Dice should only allow WeightedDie/Rollable types that I define, but that seems overly restrictive. That's what having a protocol is for.

[Samasaur1]

Especially considering that we convert the dice dictionary to an array before performing calculations anyway:

DiceKit/Sources/DiceKit/Dice.swift

Lines 385 to 392 in 5e29f59

	//Gets an array of all the dice (which can include multiple of the same die) to loop through.
	var sortedDice: [Die] = []
	for (die, count) in dice {
	for _ in 0..<count {
	sortedDice.append(die)
	}
	}
	sortedDice = sortedDice.sorted()

and when rolling we need to "expand" the dictionary anyway:

DiceKit/Sources/DiceKit/Dice.swift

Lines 313 to 322 in 5e29f59

	public func roll() -> Roll {
	var result = 0
	for (die, count) in dice {
	for _ in 0..<count {
	result += die.roll()
	}
	}
	result += modifier
	return result
	}

I see no reason why we shouldn't convert the dice dictionary to (presumably) an any Rollable array