There is IDE quick fix which suggests to copy mismatched annotation
from `expect` to `actual` (see KTIJ-26633). It needs to find
`actual` PsiElement where to add annotation. Before previous commit, it
was easy - just get source of `Incompatibility.actualSymbol`.
After previous commit, the problem might be in value parameter, while
`actualSymbol` would contain function symbol. This is solved by adding
new field `Incompatibility.actualAnnotationTargetElement`.
`SourceElementMarker` introduced, because it's needed to be used in
abstract checker. Existing `DeclarationSymbolMarker` doesn't fit
because in next PR for this issue annotations set on types will be reported,
and types are not declarations.
^KT-60671
Roman Efremov
420dceb7d8