[IR] Introduce new IdSignatures

FileSignature, CompositeSignature, LocalSignature

They are needed to make possible reference any non-local declaration via
 signature, including private signature, type parameters and so on.

- Support those new signatures in proto and klibs
- Rename `isPublic` -> `isPubliclyVisible` due to changed semantic
- Fix FIR
- clean up code

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsDeclarationTable.kt

@@ -21,17 +21,13 @@ class JsUniqIdClashTracker : IdSignatureClashTracker {
     private val committedIdSignatures = mutableMapOf<IdSignature, IrDeclaration>()
 
     override fun commit(declaration: IrDeclaration, signature: IdSignature) {
-        if (!signature.isPublic) return // don't track local ids
+        if (!signature.isPubliclyVisible) return // don't track local ids
 
         if (signature in committedIdSignatures) {
             val clashedDeclaration = committedIdSignatures[signature]!!
             val parent = declaration.parent
             val clashedParent = clashedDeclaration.parent
-            if (declaration is IrTypeParameter && parent is IrSimpleFunction && parent.parent is IrProperty && parent !== clashedParent) {
-                // Check whether they are type parameters of the same extension property but different accessors
-                require(clashedParent is IrSimpleFunction)
-                require(clashedParent.correspondingPropertySymbol === parent.correspondingPropertySymbol)
-            } else {
+            if (declaration !is IrTypeParameter || parent !is IrSimpleFunction || clashedParent !is IrSimpleFunction || parent.correspondingPropertySymbol !== clashedParent.correspondingPropertySymbol) {
                 // TODO: handle clashes properly
                 error("IdSignature clash: $signature; Existed declaration ${clashedDeclaration.render()} clashed with new ${declaration.render()}")
             }

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsMangler.kt

@@ -50,8 +50,7 @@ abstract class AbstractJsDescriptorMangler : DescriptorBasedKotlinManglerImpl()
         override fun DeclarationDescriptor.isPlatformSpecificExported() = false
     }
 
-    private class JsDescriptorManglerComputer(builder: StringBuilder, mode: MangleMode) :
-        DescriptorMangleComputer(builder, mode) {
+    private class JsDescriptorManglerComputer(builder: StringBuilder, mode: MangleMode) : DescriptorMangleComputer(builder, mode) {
         override fun copy(newMode: MangleMode): DescriptorMangleComputer = JsDescriptorManglerComputer(builder, newMode)
     }