[FIR] Get rid of FirSymbolProvider.getClassNamesInPackage

There was one non-removable usage of those function in FirJavaElementFinder
  and three non-trivial implementation
- `FirProvider.SymbolProvider`
- `KotlinDeserializedJvmSymbolsProvider`
- `FirBuiltinSymbolProvider`

First implementation was moved to `FirProvider` and other two was
  deleted, because in FirJavaElementFinder we need lookup only in
  classes from source code, so such methods in library providers are
  useless

#KT-41048

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/providers/FirIdeProvider.kt

@@ -112,6 +112,11 @@ internal class FirIdeProvider(
         TODO()
     }
 
+    override fun getClassNamesInPackage(fqName: FqName): Set<Name> {
+        // TODO: KT-41048
+        return emptySet()
+    }
+
     private inner class SymbolProvider : FirSymbolProvider() {
         override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> =
             providerHelper.getTopLevelCallableSymbols(packageFqName, name)

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/scopes/KtFirPackageScope.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.idea.frontend.api.fir.scopes
 
-import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
 import org.jetbrains.kotlin.fir.scopes.impl.FirPackageMemberScope
 import org.jetbrains.kotlin.idea.frontend.api.ValidityToken
 import org.jetbrains.kotlin.idea.frontend.api.ValidityTokenOwner
@@ -25,7 +24,6 @@ internal class KtFirPackageScope(
 ) : KtPackageScope, ValidityTokenOwner {
     private val firScope by weakRef(firScope)
     override val fqName: FqName get() = firScope.fqName
-    private val provider get() = firScope.session.firSymbolProvider
 
     override fun getCallableNames(): Set<Name> = withValidityAssertion {
         // TODO: KT-41048
@@ -33,7 +31,8 @@ internal class KtFirPackageScope(
     }
 
     override fun getClassLikeSymbolNames(): Set<Name> = withValidityAssertion {
-        provider.getClassNamesInPackage(fqName)
+        // TODO: KT-41048
+        emptySet()
     }
 
     override fun getCallableSymbols(): Sequence<KtCallableSymbol> = withValidityAssertion {