Docs/move MintToken.sol from wiki

[vivekjain23]

Description of change

This is the PR addressing moving Wiki contracts to the wasp repo. A MintToken.sol contract was added, to create a native token foundry, to be able to mint native tokens from it in future, alongside a solo test for it

How the change has been tested

A Solo test.

Make sure to provide instructions for the maintainer as well as any relevant configurations.

Change checklist

Tick the boxes that are relevant to your changes, and delete any items that are not.

• [X] I have followed the contribution guidelines for this project
• [X] I have performed a self-review of my own code
• [X] I have selected the develop branch as the target branch
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] I have checked that new and existing unit tests pass locally with my changes

[lucas-tortora]

could you rename the PR to follow the guidelines on confluence?

[lucas-tortora]

could you rename the PR to follow the guidelines on confluence?