[FIR] Replace inheritance with delegation for FirProvider and FirSymbolProvider

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaElementFinder.kt

@@ -43,12 +43,12 @@ class FirJavaElementFinder(
     private val firProvider = session.firProvider
 
     override fun findPackage(qualifiedName: String): PsiPackage? {
-        if (firProvider.getClassNamesInPackage(FqName(qualifiedName)).isEmpty()) return null
+        if (firProvider.symbolProvider.getClassNamesInPackage(FqName(qualifiedName)).isEmpty()) return null
         return PsiPackageImpl(psiManager, qualifiedName)
     }
 
     override fun getClasses(psiPackage: PsiPackage, scope: GlobalSearchScope): Array<PsiClass> {
-        return firProvider
+        return firProvider.symbolProvider
             .getClassNamesInPackage(FqName(psiPackage.qualifiedName))
             .mapNotNull { findClass(psiPackage.qualifiedName + "." + it.identifier, scope) }
             .toTypedArray()

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaModuleBasedSession.kt

@@ -49,7 +49,7 @@ class FirJavaModuleBasedSession private constructor(
                     FirSymbolProvider::class,
                     FirCompositeSymbolProvider(
                         listOf(
-                            firProvider,
+                            firProvider.symbolProvider,
                             JavaSymbolProvider(this, sessionProvider.project, scope),
                             dependenciesProvider ?: FirDependenciesSymbolProviderImpl(this)
                         )