Allow defining the package.json and license-details.json paths

[tediroca]

We are using a project structure that place the files required for the scan in this way:

• root/backend/build/reports/dependency-license/license-details.json
• root/frontend/package.json

The plugin tries to find the files directly in the root, which makes the scan fail:

• root/build/reports/dependency-license/license-details.json
• root/package.json

It would be helpful to be able to define from which locations these files should be read from.

Thanks.