Implement dice roller (interpreter)

[jharrison902]

RPG Bot should have a dice roller. This should follow the standard NdD+C format with the following features:

• NdD should roll N number of D-sided die. For example 5d6 should roll 5 6-sided dice.
• | should separate die rolls. For example "1d20 | 1d20" should roll and present the results of 2 d20 die rolls.
• ^[NdD | NdD | NdD+C | NdD+NdD] OR \max[NdD | NdD | NdD+C | NdD+NdD] should return the maximum value for a set of dice expressions.
• v[NdD | NdD | NdD+C | NdD+NdD] OR \min[NdD | NdD | NdD+C | NdD+NdD] should return the minimum value for a set of dice expressions.
• {[NdD | NdD | NdD+C | NdD+NdD]} OR \avg[NdD | NdD | NdD+C | NdD+NdD] should return the average of a set of dice expression rounded up.

[jharrison902]

Dice rolling is now committed to main. Once base functions are in, we'll move to pull requests.

[jharrison902]

Please review current code before I proceed with additional functions