Plan for 8.x-1.x (D10/D11) unstable release

Problem/Motivation

I've been asked for an unstable but soon release. But a release is something people like to have a stable API etc. This is one of the main reasons I'm careful with creating a release.

Proposed resolution

I'm open to create a unstable 8.x-1.0-alpha release to move on. But when I do this early I like to stop working on 8.x-1.x-dev branch.
By myself I will switch to a 2.x branch with a plan to get a 2.0 stable release. With this strategy people get their first unstable release and we can move on with improvements where we don't have to look on logic and api changes.

Remaining tasks

• #3324435: Create cache (file) invalidation logic
• #3325126: Boost Cacheability Settings functionality fix
• #3500752: TypeError: DrushCommands::logger()
• #3500753: ArgumentCountError: Too few arguments to function Drupal\Core\Form\ConfigFormBase::__construct()
• #3428282: Automated Drupal 11 compatibility fixes for boost