Get rid of underscores in private property names

They were used to workaround duplicate signature errors, but this is no longer
relevant since no accessors are generated for private properties with backing
fields

compiler/backend-common/src/bridges/impl.kt

@@ -47,7 +47,7 @@ public fun <Signature> generateBridgesForFunctionDescriptor(
  * eases the process of determining what bridges are already generated in our supertypes and need to be inherited, not regenerated.
  */
 private data class DescriptorBasedFunctionHandle(val descriptor: FunctionDescriptor) : FunctionHandle {
-    private val _overridden = descriptor.getOverriddenDescriptors().map { DescriptorBasedFunctionHandle(it.getOriginal()) }
+    private val overridden = descriptor.getOverriddenDescriptors().map { DescriptorBasedFunctionHandle(it.getOriginal()) }
 
     override val isDeclaration: Boolean =
             descriptor.getKind().isReal() ||
@@ -57,7 +57,7 @@ private data class DescriptorBasedFunctionHandle(val descriptor: FunctionDescrip
             descriptor.getModality() == Modality.ABSTRACT ||
             DescriptorUtils.isTrait(descriptor.getContainingDeclaration())
 
-    override fun getOverridden() = _overridden
+    override fun getOverridden() = overridden
 }