Overlaybd layer compaction

[BigVan]

What is the version of your Overlaybd

No response

What would you like to be added?

Provide overlaybd with a function to merge multiple layers and flatten them

Why is this needed for Overlaybd?

Some use cases:

• Only the newest data is needed when using overlaybd for the incremental compilation. In this situation, keeping the layered view of overlaybd image will lead to additional storage overhead.

• Support flattened convert in userspace convertor

Are you willing to submit PRs to contribute to this feature?

• Yes, I am willing to implement it.