Add option to enable/disable images

[lucacome]

This is a feature request. Would it be possible to add options to images, similar to tags?

example:

images: |
	name=myapp/foo,enable=${{ startsWith(github.ref, 'refs/tags') }}
	name=other/registry,enable=${{ github.event_name == 'pull_request' }}

or even:

images: |
	name=myapp/foo,event=tag
	name=other/registry,event=pr

Thanks!

[crazy-max]

@lucacome Yes in the first version of this action the images were merged to the tags input but the config was too verbose. An enable type for images sgtm though.

Will think about a filter type for images where you could filter by event.

[Xerkus]

Since this is GHA action, I think if for conditional expression would be more consistent: if=${{ startsWith(github.ref, 'refs/tags') }}

[crazy-max]

@lucacome I have started smth in #193 if you want to take a look.

Can be tested with crazy-max/docker-metadata-action@images-opts. Docs: https://github.com/crazy-max/docker-metadata-action/tree/images-opts#images-input

[lucacome]

I'll take a look, thanks!