Allow @ShowkaseComposable as annotation for annotation class

[ln-12]

Hey, I have a feature request which is kind of related to #233.

The @Preview annotation can be used for functions and other annotation classed (see here). @ShowkaseComposable can only be used for functions. I would like to do the following:

// some other annotations
@ShowkaseComposable
annotation class DefaultPreview

This is already possible with @Preview. Do you see any issues when allowing @ShowkaseComposable on annotation classes to achieve that? I think the only thing needed for that would be to add AnnotationTarget.ANNOTATION_CLASS here.

[vinaygaba]

@oas004 Any chance you could add the same functionality to ShowkaseComposable as well? Trying to remember why you didn't add this in the original PR's itself?

[oas004]

Hey, I think I just might have forgotten to add that as well in the initial PRs. I think that should be possible, but I'm not sure that it is as easy as just adding AnnotationTarget.ANNOTATION_CLASS. I can try to look into it this weekend if that is okay? :)

Do you think it would make sense to add the repeatable pattern as well to this annotation? So that this is possible?

@ShokaseComposable
@ShowkaseComposable
annotation class DefaultPreview

and

@ShokaseComposable
@ShowkaseComposable
@Composable
fun SomePreview()

[ReginFell]

Do you have any updates on this by any chance? This would be extremely useful for us since we want to use the ShowkaseComposable annotation across different modules, but we want to hide its configuration.

@ShowkaseComposable(tags = listOf(specialTag)
annotation class HasSpecialTag

@HasSpecialTag
@Composable
fun SomePreview()