Component version constraints are out-dated

Problem/Motivation

Performing some experimentation for this issue: #2643110: Have drupalci_testbot require drupal/core-plugin in composer.json

..I discovered that requiring drupal/core-plugin leads to a couple of problems.

1) Drupalci_testbot also needs drupal/core-annotation, which isn't a requirement of core-plugin. I'm not sure if that's an error of plugin's composer.json or not. But I just added requires: drupal/core-annotation to the testbot's composer.json.

2) Trying to composer update for annotation, we get problems like this:

  Problem 1
    - drupal/core-annotation 8.3.1 requires drupal/core-filecache ~8.2 -> no matching package found.
    - drupal/core-annotation 8.3.0 requires drupal/core-filecache ~8.2 -> no matching package found.
    - Installation request for drupal/core-annotation 8.3.* -> satisfiable by drupal/core-annotation[8.3.0, 8.3.1].

Apparently the new subtree split assigns the release value to the packages, but they all require old package versions.

Proposed resolution

A couple of ideas:

Add a step to the core release process where all these dependencies are re-versioned for the new release. Seems tedious.

Make the versioning open-ended, so that instead of specifying ~8.2, we specify >=8 or something similar.

Remaining tasks

User interface changes

API changes

Data model changes