Objc header generation public api

* Implement Obj-C header generator for public use
* Fix duplicated top level functions in an exported obj-c header

Co-authored-by: Aydar Mukhametzyanov <aydar.mukhametzyanov@jetbrains.com>

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/descriptors/LegacyDescriptorUtils.kt

@@ -140,7 +140,7 @@ private fun getPackagesFqNames(module: ModuleDescriptor): Set<FqName> {
 
 fun ModuleDescriptor.getPackageFragments(): List<PackageFragmentDescriptor> =
         getPackagesFqNames(this).flatMap {
-            getPackage(it).fragments.filter { it.module == this }
+            getPackage(it).fragments.filter { it.module == this }.toSet()
         }
 
 val ClassDescriptor.enumEntries: List<ClassDescriptor>

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/ObjCExportLazy.kt

@@ -426,7 +426,7 @@ private abstract class LazyObjCProtocol(
         get() = realStub.superProtocols
 }
 
-private fun createNamerConfiguration(configuration: ObjCExportLazy.Configuration): ObjCExportNamer.Configuration {
+internal fun createNamerConfiguration(configuration: ObjCExportLazy.Configuration): ObjCExportNamer.Configuration {
     return object : ObjCExportNamer.Configuration {
         override val topLevelNamePrefix = abbreviate(configuration.frameworkName)
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/ObjcExportHeaderGeneratorMobile.kt

@@ -0,0 +1,45 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.ModuleDescriptor
+import org.jetbrains.kotlin.resolve.deprecation.DeprecationResolver
+
+class ObjcExportHeaderGeneratorMobile internal constructor(
+        moduleDescriptors: List<ModuleDescriptor>,
+        mapper: ObjCExportMapper,
+        namer: ObjCExportNamer,
+        private val warningCollector: ObjCExportWarningCollector,
+        objcGenerics: Boolean
+) : ObjCExportHeaderGenerator(moduleDescriptors, mapper, namer, objcGenerics) {
+
+    companion object {
+        fun createInstance(
+                configuration: ObjCExportLazy.Configuration,
+                warningCollector: ObjCExportWarningCollector,
+                builtIns: KotlinBuiltIns,
+                moduleDescriptors: List<ModuleDescriptor>,
+                deprecationResolver: DeprecationResolver? = null): ObjCExportHeaderGenerator {
+
+            val mapper = ObjCExportMapper(deprecationResolver, local = true)
+            val namerConfiguration = createNamerConfiguration(configuration)
+            val namer = ObjCExportNamerImpl(namerConfiguration, builtIns, mapper, local = true)
+
+            return ObjcExportHeaderGeneratorMobile(
+                    moduleDescriptors,
+                    mapper,
+                    namer,
+                    warningCollector,
+                    configuration.objcGenerics)
+        }
+    }
+
+    override fun reportWarning(text: String) {
+        warningCollector.reportWarning(text)
+    }
+
+    override fun reportWarning(method: FunctionDescriptor, text: String) {
+        warningCollector.reportWarning(method, text)
+    }
+
+}