Introduce KClass-based cache for KPackageFragment

* It is a heavy-weight object that is hard to compute
* It is being constructed each type _cached_ method ref is used in equals/hashCode
* Module name is deliberately ignored, corresponding doc is added where appropriate 

#KT-48136

Merge-request: KT-MR-6817
Merged-by: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -41267,6 +41267,18 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/reflection"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
         }
 
+        @Test
+        @TestMetadata("jvmKPackageCaching.kt")
+        public void testJvmKPackageCaching() throws Exception {
+            runTest("compiler/testData/codegen/box/reflection/jvmKPackageCaching.kt");
+        }
+
+        @Test
+        @TestMetadata("jvmKTypeCaching.kt")
+        public void testJvmKTypeCaching() throws Exception {
+            runTest("compiler/testData/codegen/box/reflection/jvmKTypeCaching.kt");
+        }
+
         @Nested
         @TestMetadata("compiler/testData/codegen/box/reflection/annotations")
         @TestDataPath("$PROJECT_ROOT")