Expose block cost calculation to the bindings

[begonaalvarezd]

Description

In the explorer we would like to add the mana each block burned, and for that we would need a way to calculate the "mana block cost"

Motivation

Above mentioned

Requirements

Write a list of what you want this feature to do.

Open questions (optional)

Use this section to ask any questions that are related to the feature.

Are you planning to do it yourself in a pull request?

Yes/No.