Oniro Migration: bitbake shared-state-cache working and strategy

Investigation around bitbake cache management:

• How it works?
• How it grows up?
• What is the Oniro team strategy about invalidating cache, ttl, metrics on sizing evolution, ...?

Documentations:

• https://stackoverflow.com/questions/31748577/how-does-shared-state-cache-in-yocto-work
• https://docs.yoctoproject.org/overview-manual/concepts.html#shared-state-cache
• https://docs.yoctoproject.org/dev-manual/common-tasks.html#invalidating-shared-state-to-force-a-task-to-run