Workaround missing complitions due to non-backportable change in the upstream. Update CompletionTests

Author: WojciechMazur

presentation-compiler/src/main/dotty/tools/pc/completions/Completions.scala

@@ -231,7 +231,14 @@ class Completions(
       label: String,
       toCompletionValue: (String, SingleDenotation, CompletionSuffix) => CompletionValue
   ): List[CompletionValue] =
-    val sym = denot.symbol
+    // Workaround for LTS due to lack of https://github.com/scala/scala3/pull/18874 backport
+    // required after backport of https://github.com/scala/scala3/pull/18914
+    // We use the symbol of accessor result type to make the sym compliant with the 3.4+
+    // where we would obtain the field symbol directly
+    val sym =
+      val resultTpeSym = denot.info.finalResultType.typeSymbol
+      if denot.symbol.is(Accessor) && resultTpeSym != NoSymbol then resultTpeSym
+      else denot.symbol
     // find the apply completion that would need a snippet
     // <accessor> handling is LTS specific: It's a workaround to mittigate lack of https://github.com/scala/scala3/pull/18874 backport
     // which was required in backport of https://github.com/scala/scala3/pull/18914 to achive the improved completions semantics.