[K2/N] Add ObjCExport test for kdoc strings

^KT-56090

Merge-request: KT-MR-9926
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

native/native.tests/testData/ObjCExport/kdocExport/kdocExport.filter.txt

@@ -0,0 +1 @@
+EXPORT_KDOC

native/native.tests/testData/ObjCExport/kdocExport/kdocExport.gold.txt

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+ * `Summary class` [KDocExport]. // EXPORT_KDOC
+ * @property xyzzy Doc for property xyzzy // EXPORT_KDOC
+ * @property zzz See below. // EXPORT_KDOC
+/** Non-primary ctor KDoc: // EXPORT_KDOC */
+/** @property xyzzy KDoc for foo? // EXPORT_KDOC */
+ * @param xyzzy is documented. // EXPORT_KDOC
+ * This is multi-line KDoc. See a blank line above. // EXPORT_KDOC
+/** @property foo KDoc for yxxyz? // EXPORT_KDOC */
+ * Kdoc for a property // EXPORT_KDOC
+ * Useless function [whatever] // EXPORT_KDOC
+ * This kdoc has some additional formatting. // EXPORT_KDOC
+ * @param a keep intact and return // EXPORT_KDOC
+ * @return value of [a] // EXPORT_KDOC
+ * Check for additional comment (note) below // EXPORT_KDOC

native/native.tests/testData/ObjCExport/kdocExport/kdocExport.kt

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+// KT-56090: [K2/N] Emit DocString klib extensions for ObjCExport
+// MUTED_WHEN: K2
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kdocExport
+
+/**
+ * `Summary class` [KDocExport]. // EXPORT_KDOC
+ *
+ * @property xyzzy Doc for property xyzzy // EXPORT_KDOC
+ * @property zzz See below. // EXPORT_KDOC
+ */
+
+// Expected: this comment shall not affect KDoc (i.e. kdoc above is still OK)
+class KDocExport() {
+    /**
+     * @param xyzzy is documented. // EXPORT_KDOC
+     *
+     * This is multi-line KDoc. See a blank line above. // EXPORT_KDOC
+     */
+    val xyzzy: String = "String example"
+
+    /** Non-primary ctor KDoc: // EXPORT_KDOC */
+    constructor(name: String) : this() {
+        println(name)
+    }
+
+    /** @property xyzzy KDoc for foo? // EXPORT_KDOC */
+    val foo = "foo"
+    /** @property foo KDoc for yxxyz? // EXPORT_KDOC */
+    var yxxyz = 0;
+}
+
+
+/**
+ * Useless function [whatever] // EXPORT_KDOC
+ *
+ * This kdoc has some additional formatting. // EXPORT_KDOC
+ * @param a keep intact and return // EXPORT_KDOC
+ * @return value of [a] // EXPORT_KDOC
+ * Check for additional comment (note) below // EXPORT_KDOC
+ */
+fun whatever(a:String) = a
+
+public abstract class SomeClassWithProperty
+{
+    /**
+     * Kdoc for a property // EXPORT_KDOC
+     */
+    public abstract val heavyFormattedKDocFoo: SomeClassWithProperty
+}