[IR] Extract descriptor part from SymbolTable into separate component

After this change SymbolTable (and ReferenceSymbolTable) contains only
  methods with IdSignatures. All descriptors-related methods are moved
  into DescriptorSymbolTableExtension, which automatically delegates to
  the SymbolTable if needed

At this moment there are cross-references between SymbolTable, because
  descriptor API is still actively used across backends. So SymbolTable
  is accessible in some place then descriptor extension will be accessible
  too

DescriptorSymbolTableExtension is an implementation of abstract SymbolTableExtension
  which allows to implement different kinds of storages, e.g. FIR based
  (it probably will be needed for FIR2IR)

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/linkage/issues/checks.kt

@@ -9,7 +9,6 @@ import org.jetbrains.kotlin.backend.common.serialization.KotlinIrLinker
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.ir.util.SymbolTable
-import org.jetbrains.kotlin.ir.util.allUnbound
 import org.jetbrains.kotlin.ir.util.irMessageLogger
 
 // N.B. Checks for absence of unbound symbols only when unbound symbols are not allowed.
@@ -18,14 +17,14 @@ fun KotlinIrLinker.checkNoUnboundSymbols(symbolTable: SymbolTable, whenDetected:
 
 // N.B. Always checks for absence of unbound symbols. The condition whether this check should be applied is controlled outside.
 fun IrMessageLogger.checkNoUnboundSymbols(symbolTable: SymbolTable, whenDetected: String) {
-    val unboundSymbols = symbolTable.allUnbound
+    val unboundSymbols = symbolTable.descriptorExtension.allUnboundSymbols
     if (unboundSymbols.isNotEmpty())
         UnexpectedUnboundIrSymbols(unboundSymbols, whenDetected).raiseIssue(this)
 }
 
 // N.B. Always checks for absence of unbound symbols. The condition whether this check should be applied is controlled outside.
 fun CompilerConfiguration.checkNoUnboundSymbols(symbolTable: SymbolTable, whenDetected: String) {
-    val unboundSymbols = symbolTable.allUnbound
+    val unboundSymbols = symbolTable.descriptorExtension.allUnboundSymbols
     if (unboundSymbols.isNotEmpty())
         UnexpectedUnboundIrSymbols(unboundSymbols, whenDetected).raiseIssue(irMessageLogger)
 }

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/linkage/partial/PartialLinkageSupportForLinkerImpl.kt

@@ -15,7 +15,6 @@ import org.jetbrains.kotlin.ir.linkage.partial.PartialLinkageLogger
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.ir.util.SymbolTable
-import org.jetbrains.kotlin.ir.util.allUnbound
 
 fun createPartialLinkageSupportForLinker(
     partialLinkageConfig: PartialLinkageConfig,
@@ -73,7 +72,7 @@ internal class PartialLinkageSupportForLinkerImpl(
 
     private fun generateStubsAndPatchUsagesInternal(symbolTable: SymbolTable, patchIrTree: () -> Unit) {
         // Generate stubs.
-        for (symbol in symbolTable.allUnbound) {
+        for (symbol in symbolTable.descriptorExtension.allUnboundSymbols) {
             stubGenerator.getDeclaration(symbol)
         }
 

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IncrementalCompilationSupport.kt

@@ -145,7 +145,7 @@ class CurrentModuleWithICDeserializer(
 
     override fun init(delegate: IrModuleDeserializer) {
         val knownBuiltIns = irBuiltIns.knownBuiltins.map { (it as IrSymbolOwner).symbol }.toSet()
-        symbolTable.forEachDeclarationSymbol {
+        symbolTable.descriptorExtension.forEachDeclarationSymbol {
             assert(it.isPublicApi)
             if (it.descriptor.isDirtyDescriptor()) { // public && non-deserialized should be dirty symbol
                 if (it !in knownBuiltIns) {
@@ -172,4 +172,4 @@ class CurrentModuleWithICDeserializer(
     override fun fileDeserializers(): Collection<IrFileDeserializer> {
         return delegate.fileDeserializers()
     }
-}
+}