Provide stable JVM names for kotlinx-metadata file facades

#KT-23198

libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/jvmMetadataUtil.kt

@@ -3,6 +3,7 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
+@file:JvmName("JvmMetadataUtil")
 package kotlinx.metadata.jvm
 
 import kotlinx.metadata.ClassName

libraries/kotlinx-metadata/src/kotlinx/metadata/ClassName.kt

@@ -3,6 +3,7 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
+@file:JvmName("ClassNameKt")
 package kotlinx.metadata
 
 /**

libraries/kotlinx-metadata/src/kotlinx/metadata/Flags.kt

@@ -3,6 +3,7 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
+@file:JvmName("FlagsKt")
 package kotlinx.metadata
 
 /**