[AA Standalone] Consider type aliases in direct inheritors search

A type alias may still be inherited from. For example:

```
sealed class MyClass

typealias T = MyClass

class Inheritor : T() // `Inheritor` is a direct inheritor of `MyClass`.
```

The index is a simplified version of the IDE's
`KotlinTypeAliasByExpansionShortNameIndex`, but it should be sufficient
for virtually all cases.

^KT-66013

analysis/analysis-api-standalone/analysis-api-fir-standalone-base/src/org/jetbrains/kotlin/analysis/api/standalone/base/providers/KotlinStandaloneDirectInheritorsProvider.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.fir.resolve.providers.symbolProvider
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.KtClass
 import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.psiUtil.contains
@@ -42,7 +43,11 @@ class KotlinStandaloneDirectInheritorsProvider(private val project: Project) : K
         includeLocalInheritors: Boolean,
     ): Iterable<KtClassOrObject> {
         val classId = ktClass.getClassId() ?: return emptyList()
-        val possibleInheritors = staticDeclarationProviderFactory.getDirectInheritorCandidates(classId.shortClassName)
+
+        val aliases = mutableSetOf(classId.shortClassName)
+        calculateAliases(classId.shortClassName, aliases)
+
+        val possibleInheritors = aliases.flatMap { staticDeclarationProviderFactory.getDirectInheritorCandidates(it) }
 
         if (possibleInheritors.isEmpty()) {
             return emptyList()
@@ -65,6 +70,16 @@ class KotlinStandaloneDirectInheritorsProvider(private val project: Project) : K
         return possibleInheritors.filter { isValidInheritor(it, baseFirClass, scope, includeLocalInheritors) }
     }
 
+    private fun calculateAliases(aliasedName: Name, aliases: MutableSet<Name>) {
+        staticDeclarationProviderFactory.getInheritableTypeAliases(aliasedName).forEach { alias ->
+            val aliasName = alias.nameAsSafeName
+            val isNewAliasName = aliases.add(aliasName)
+            if (isNewAliasName) {
+                calculateAliases(aliasName, aliases)
+            }
+        }
+    }
+
     private fun isValidInheritor(
         candidate: KtClassOrObject,
         baseFirClass: FirClass,