Maintain a list of known (non-deposited?) package dev repos in this repository

[wilfwilson]

This could be used:

• To help automatically generate all of the information at gap-packages.github.io (currently, it is partially manual).
• In the tests at gap-infra/integration which test dev versions of packages.

Some thoughts:

• The package development repositories of deposited packages should be listed in their PackageInfo.g files. Therefore we don't need to store this.
• Those hosted at gap-packages could be generated dynamically, if we wanted to.
• (What do we do if a package repo is moved or renamed?)

Perhaps this should be kept in JSON format. We could additionally store whether to test the package at gap-infra/integration, and perhaps whether to display the link on https://gap-packages.github.io.

[fingolfin]

A variation of this we discussed at the last GAP Days:

• add many more packages to this repo (basically any we know of)
• but keep a separate list that controls which of these packages actually are to be distributed with GAP
• assembling tarballs of course would only take packages which are on the distro list
• for tests, distributed packages would be tested exactly as right now, i.e. *only with/against other distributed packages
• for not distributed packages, we would install just that package in addition to all distributed packages
  • we might run fewer tests for those packages, to conserve resources and also to reflect that we make fewer guarantees for such packages
  • OTOH it might be useful to run all the usual tests to get an idea of "how compatible" a package is with the packages in the official distro