Support multiple cache-from arguments

[AdeelK93]

Description

Docker supports multiples caches - but there isn't really a way to provide multiple cache-from arguments.

One solution may be to allow sequences in the cache-from, perhaps like:

cache-from:
- type=registry,ref=<registry>/<cache-image>:<branch>
- type=registry,ref=<registry>/<cache-image>:main 

[crazy-max]

This is actually supported but correct syntax is:

cache-from: |
  type=registry,ref=<registry>/<cache-image>:<branch>
  type=registry,ref=<registry>/<cache-image>:main