RFC: Fetching module

[geaaru]

Hereinafter, the list of features to implement:

• [x] Local repositories

• [x] HTTP/HTTPs repositories

• [ ] Integrate support of aggregate download per repository

• [x] Integrate support of custom Authentication support (Basic, Token, etc.)

• [ ] Fetching packages from multiple sources (FTP, HTTP, Object Store, Directory)

• [ ] Support incremental download for package revisions

• [ ] Support Proxy Configuration

• [ ] Support --fetchonly option for prepare cache directory to use in offline env

• [x] Mirror list for repository must be a separated file more easy to update through a package

• [x] Integrity check / packages verification

[mudler]

Client implementations are in: https://github.com/mudler/luet/tree/master/pkg/installer/client

[geaaru]

Authentication support added with c353ab49787e4d07af3fbce720e0b9d722d8c33f

[geaaru]

The mirrors list could be defined with a specific file for the repository. Mark as ok.