Export CompatFilePath and CompatLicenseFile

[andreabedini]

These two types need to be exported for users to be able to define their own FieldGrammar.

---

Please include the following checklist in your PR:

• [ ] Patches conform to the coding conventions.
• [ ] Any changes that could be relevant to users have been recorded in the changelog.
• [ ] The documentation has been updated, if necessary.

Please also shortly describe how you tested your change. Bonus points for added tests!