Generic license finder file

[kaystrobach]

Problem to solve

• use license finder for all possible package managers with a package manager specific plugin

Further details / Proposal

• currently license finder tries to implement package manager specific code by reading the lock files
• the package managers natively also support licenses and most of them (like composer and yarn) allow to run scripts directly after an install or upgrade
• these scripts / plugins should be used to let the package manager extract the license information in a file with the following naming convention: license.<packagemanager>.json which can then be committed to the repo easily.
• this also reduces the complexity, as the license report generator can be set as dev dependency
• additionally the maintainers of the package managers may natively support the license information generation

this architecture is already used by the gradle plugin:

• https://github.com/pivotal-legacy/LicenseFinder#gradle-projects

What does success look like, and how can we measure that?

• define format for license.<packagemanager>.json
• read format and add it to the license report

Relations

• related #518 (composer licenses)