feat(run): allow multiple script targets to be triggered at once

[JamesHenry]

Description

Because the modern task-runner in lerna understands how tasks relate to one another we can safely trigger multiple script targets at once.

This can be a really nice convenience and avoid the need to use a utility such as npm-run-all just for this case.

Motivation and Context

How Has This Been Tested?

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)
• Chore (change that has absolutely no effect on users)

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.