Add support for Ctrl keys via `userEvent.keyboard`

[nicklemmon]

Describe the feature you'd like:

Support for the [Ctrl] special key to help handle process cancelation

userEvent.keyboard('[Ctrl]c').

Suggested implementation:

Add the Ctrl keys to the keyMap.ts config

Describe alternatives you've considered:

There is no alternative that I am aware of - perhaps using fireEvent could work?

Teachability, Documentation, Adoption, Migration Strategy:

Documentation would need to be added to:
https://cli-testing.com/guides/user-event/#keyboardinstance-text-options