Extension: token supply controls - mint, burn

[ureeves]

In many situation, it is desirable to have an account (or multiple) be able to control the supply of the token. Functions enabling such functionality are usually called mint and burn, for increasing and decreasing the supply of the token respectively.

It is likely a must to specify how to use allow/denylists before this can be specified. As an alternative, we could also use a simple owner mechanism, where only a single account - defined at construction time - is allowed to perform these actions.