Add new additional library

There are 2 different types of additional libraries:

Additional libraries which are following the Qt release schedule
Additional libraries which are released independently (with their own release schedule)

Additional libraries which are following the Qt release schedule:

Follows Qt release versioning
Follows Qt milestones, quality gates & release plan
- Means new feature development must be ready at Qt Feature Freeze
Full CI must be in the use before FF
- Means same targets with Qt release is used
Packages are tested together with the pre-releases (alpha, beta etc)

Additional libraries released independently:

Must have its own version numbering scheme (to clearly indicate it isn't part of any Qt release)
Must have its own release plan and schedule
- Should have common pre-release milestones (FF, Alpha, Beta, RC) but in its own schedule
Release plan should be agreed with library maintainer & release team & documented in the Jira
Can't disturb Qt release

Adding new additional library to be available with Qt

It is maintainer's responsibility to start discussion about adding a new additional library
Adding a new additional library starts from agreement if it will be part of Qt release or released separately (see definition above)
There should be a Jira task for every new additional library (Like QTBUG-90375)
- This task should contain all needed tasks to be done
When additional library has a CI in use release team can start packaging tasks
- Release team must be notified about that as soon as possible