[test-runner-cli] allow watch mode with non-tty terminals

[LarsDenBakker]

When using task runners the terminal is not interactive. We should still allow watch mode in these cases.

[keviddles]

Just hit this myself.

I copied the command from here:

concurrently --kill-others --names tsc,wtr \"npm run tsc:watch\" \"wtr --watch\"

into an npm script and got:

[wtr] Error while running tests:
[wtr] Error: Cannot run watch mode in a non-interactive (TTY) terminal.

EDIT: I also had to change the sample command to tsc --watch instead of tsc:watch

[benjamind]

This also cropped up for me too recently, would it be possible to raise the priority on this. What would the changes necessary be?