Show actions for handling a `private val ComponentStyle/ComponentVariant/Keyframes`

[bitspittle]

See the important note in this section: https://github.com/varabyte/kobweb?tab=readme-ov-file#componentstyle

In other words, detect this case:

private val SomeStyle by ComponenStyle

then put a warning on the "private" keyword and add two actions the user can take

1) Remove the "private" modifier 2) Introduce an initSilk method (or add to the end of an existing one if already defined)

@Suppress("PRIVATE_COMPONENT_STYLE")
private val SomeCustomStyle by ComponentStyle { /* ... */ }

@InitSilk
fun registerPrivateStyle(ctx: InitSilkContext) {
  ctx.theme.registerComponentStyle(SomeCustomStyle)
}