Add support for annotations in type ascriptions

The following snippet contains an annotation `Anno` but KSP does not pick it up.
```kotlin
@Target(AnnotationTarget.TYPE)
annotation class Anno

val myVal: (@Anno String) -> Unit = { str -> println(str) }
```

`KSTypeReference` is already a subtype of `KSAnnotated` so it shouldn't be that difficult to extend it to type ascriptions.