[lldb/Interpreter] Fix deep copying for OptionValue classes

Some implementations of the DeepCopy function called the copy constructor that copied m_parent member instead of setting a new parent. Others just leaved the base class's members (m_parent, m_callback, m_was_set) empty.
One more problem is that not all classes override this function, e.g. OptionValueArgs::DeepCopy produces OptionValueArray instance, and Target[Process/Thread]ValueProperty::DeepCopy produces OptionValueProperty. This makes downcasting via static_cast invalid.

The patch implements idiom "virtual constructor" to fix these issues.
Add a test that checks DeepCopy for correct copying/setting all data members of the base class.

Differential Revision: https://reviews.llvm.org/D96952

lldb/source/Target/Process.cpp

@@ -83,16 +83,10 @@ using namespace std::chrono;
 #define DISABLE_MEM_CACHE_DEFAULT true
 #endif
 
-class ProcessOptionValueProperties : public OptionValueProperties {
+class ProcessOptionValueProperties
+    : public Cloneable<ProcessOptionValueProperties, OptionValueProperties> {
 public:
-  ProcessOptionValueProperties(ConstString name)
-      : OptionValueProperties(name) {}
-
-  // This constructor is used when creating ProcessOptionValueProperties when
-  // it is part of a new lldb_private::Process instance. It will copy all
-  // current global property values as needed
-  ProcessOptionValueProperties(ProcessProperties *global_properties)
-      : OptionValueProperties(*global_properties->GetValueProperties()) {}
+  ProcessOptionValueProperties(ConstString name) : Cloneable(name) {}
 
   const Property *GetPropertyAtIndex(const ExecutionContext *exe_ctx,
                                      bool will_modify,
@@ -131,10 +125,12 @@ enum {
 #include "TargetPropertiesEnum.inc"
 };
 
-class ProcessExperimentalOptionValueProperties : public OptionValueProperties {
+class ProcessExperimentalOptionValueProperties
+    : public Cloneable<ProcessExperimentalOptionValueProperties,
+                       OptionValueProperties> {
 public:
   ProcessExperimentalOptionValueProperties()
-      : OptionValueProperties(
+      : Cloneable(
             ConstString(Properties::GetExperimentalSettingsName())) {}
 };
 
@@ -157,8 +153,8 @@ ProcessProperties::ProcessProperties(lldb_private::Process *process)
         ConstString("thread"), ConstString("Settings specific to threads."),
         true, Thread::GetGlobalProperties()->GetValueProperties());
   } else {
-    m_collection_sp = std::make_shared<ProcessOptionValueProperties>(
-        Process::GetGlobalProperties().get());
+    m_collection_sp =
+        OptionValueProperties::CreateLocalCopy(*Process::GetGlobalProperties());
     m_collection_sp->SetValueChangedCallback(
         ePropertyPythonOSPluginPath,
         [this] { m_process->LoadOperatingSystemPlugin(true); });