chore: add .mocharc.json

[rickstaa]

What does this pull request do? Explain your changes. (required)

This pull request adds a .mocharc.json configuration file so that mocha hardhat tests can be directly debugged in VScode.

Specific updates (required)

• Added .mocharc.json mocha config file.

How did you test each of these updates (required)

I checked that I can with this file now debug the smart contract tests.

Does this pull request close any open issues?

No

Checklist:

• [x] README and other documentation updated
• [x] All tests using yarn test pass