cli: create a course management tool for teachers

[meling]

Create a new CLI tool for various tasks related to managing QuickFeed repositories:

• support making readme files for labs
• support creating issues for tasks to be completed by PRs
• initialize repositories (see dat320/setup folder)
• should ensure to sanitize the various files to remove solution build tags
• should replace {{ .CourseTag }} entries in markdown files with course-year (see dat320/setup)
• support synchronizing from the base repository to assignments, tests and info repositories
• support for synchronizing from base repository to a test student's assignment repository
• should be made as generic as possible; so that it can work for many courses using different languages etc
• should use sub-commands similar to gh and git (find a suitable library for managing sub-commands and config, e.g., viper)

To be revised.

• decide on a name for the tool
• design API for tool:
  • cm sync lab6 assignments
  • cm sync lab6 tests assignments
  • cm sync info
  • cm readme lab6

This should replace all the Makefile and scripts used across our courses.

[JosteinLindhom]

Google's subcommands library is a lightweight command library.

[meling]

The teacher CLI tool should have subcommands to

• [ ] download (clone) a list of repositories (based on user names or group names),
• [ ] download (clone) all repositories and
• [ ] download all repos as zip balls for archival purposes. The GetZipballURL function can possibly be used. However, check if this specifically needs the student to perform a release. Ideally, the student shouldn't have to do anything other than to push their final version...