Introduce JvmMemberSignature to represent name and desc of jvm methods and fields

Return member name and desc in a class in order not to parse that information
from concatenated string when required.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/lightClasses/LightMemberOriginForCompiledElement.kt

@@ -156,8 +156,8 @@ private object ByJvmSignatureIndexer : DecompiledTextIndexer<ClassNameAndSignatu
         }
 
         if (descriptor is DeserializedSimpleFunctionDescriptor) {
-            JvmProtoBufUtil.getJvmMethodSignature(descriptor.proto, descriptor.nameResolver, descriptor.typeTable)?.let {
-                val signature = MemberSignature.fromMethodNameAndDesc(it)
+            JvmProtoBufUtil.getJvmMethodSignature(descriptor.proto, descriptor.nameResolver, descriptor.typeTable)?.let { it ->
+                val signature = MemberSignature.fromMethodNameAndDesc(it.toString())
                 save((descriptor.containingDeclaration as? ClassDescriptor)?.relativeClassName().orEmpty(), signature)
             }
         }