[FE, IR] Store PsiElement for mismatched annotation's actual target

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

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/FirSourceElement.kt

@@ -0,0 +1,11 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir
+
+import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.mpp.SourceElementMarker
+
+class FirSourceElement(val element: KtSourceElement?) : SourceElementMarker