fix(import): Avoid "unrecognized input" error from colors when using --flatten

[fc]

Resolves issue when color in the output would create invalid output

Description

Motivation and Context

Resolves the same or similar problem described here:
#1644

Basically, calling git log would contain colorized output that leads to problems when calling git am ...

Note: It resolves only when the --flatten parameter is set!

Kudos to random StackOverflow dude who pointed me in the direction of the right fix:
https://stackoverflow.com/a/53191568/747678

How Has This Been Tested?

I checked out the lerna repos locally, made the change, used npm link and ran lerna import --flatten some-dir that way to see the import worked successfully. Also ran integration test npm run integration -- lerna-import.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[evocateur]

LGTM