feat(depcruise): add license check rules

[sverweij]

Description

• Adds a 'license' property to cruised modules that have one.
• Adds 'license' and 'licenseNot' rule elements to enable black- and whitelisting of license types.

Motivation and Context

To be able to flag dependent modules that have licenses that are e.g. not compatible with your own license or with the policies within your company.

(Inspired by https://github.com/franciscop/legally - which scans everything in your module and lists the licenses.)

How Has This Been Tested?

• Unit tests
• Dependency-cruiser's own ruleset has a check (it can't use GPL licensed modules as it's MIT licensed and GPL doesn't consider MIT to be compatible with it a.f.a.i.k.).

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• The code I add will be subject to The MIT license, and I'm OK with that.
• The code I've added is my own original work.
• 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.