linuxkit

Datasource providers

This is a fork from linuxkit including only a refactored version of the datasource providers logic.

Notable changes are:

• Inclusion of an abandoned PR.
• The code is refactored so datasource providers are part of an importable golang providers package.
• Few fixes and adaptations have been incorporated as needed.
• Only datasource providers or the former metadata package code is kept, all ther rest is dropped.