How to Use --parallel from Mocha 8 [Feature]

[johnnyshankman]

• I'd be willing to implement this feature

Describe the user story

As a user,
When I have Mocha 8+ installed
And I'd like to parallelize my tests
I expect there to be a CLI flag for that
Because Mocha 8+ has a --parallel option

Describe the solution you'd like

A --parallel flag to invoke the parallel option or a clear way to pass commands to the original mocha command.

Describe the drawbacks of your solution

First one only works with Mocha 8+

Describe alternatives you've considered

Second one works with all

Additional context

Want to speed up my vue-cli made application's tests.