Ignore pre-cached images

[pl4nty]

Is your feature request related to a problem? Please describe.
Hosted runners come with common base images built-in, but the action appears to restore and save them anyway. This only causes unnecessary delays with smaller Linux images, but large Windows images can cause disk space exhaustion during saving and failure to save any layers.

Describe the solution you'd like
It would be great if the action could ignore base cached images, but detecting this could be challenging, especially if the same action runs across multiple runner types. Maybe an option could be created to ignore specific layers by digest? Then users could manually specify the layers they'd like to ignore.

Describe alternatives you've considered
I'm currently attempting to delete the built-in images at the end of my builds, so they're not saved by the post-build step. If a technical solution isn't possible, maybe this approach could be added to the README?

[jpribyl]

I will try to take a look at this when I have some time, in the meantime feel free to open a PR for it 😃 would be happy to add you on as a collaborator