[lldb] Refine call to decl printing helper (NFC)

[kastiglione]

Summary

When ValueObjectPrinter calls its m_decl_printing_helper, not all state is passed to
the helper. In particular, the helper doesn't have access to m_curr_depth, and thus
can't act on the logic within ShouldShowName.

To address this, this change passes in a modified copy of m_options. The modified copy
has has m_hide_name set according to the results of ShouldShowName. This allows
helper functions to know whether the name should be shown or hidden, without having
access to ValueObjectPrinter's full state.

This is NFC in mainline lldb, as the only decl printing helper doesn't make use of this.
However in swift-lldb at least, there are decl printing helpers that do need this
information passed to them. See https://github.com/apple/llvm-project/pull/6795 where a
test is also included.

lldb/source/DataFormatters/ValueObjectPrinter.cpp

if (Language *lang_plugin = Language::FindPlugin(lang_type)) {
       m_options.m_decl_printing_helper = lang_plugin->GetDeclPrintingHelper();
     }
   }
 
   if (m_options.m_decl_printing_helper) {
     ConstString type_name_cstr(typeName.GetString());
     ConstString var_name_cstr(varName.GetString());
 
+    DumpValueObjectOptions decl_print_options = m_options;
+    // Pass printing helpers an option object that indicates whether the name
+    // should be shown or hidden.
+    decl_print_options.SetHideName(!ShouldShowName());
+
     StreamString dest_stream;
     if (m_options.m_decl_printing_helper(type_name_cstr, var_name_cstr,
-                                         m_options, dest_stream)) {
+                                         decl_print_options, dest_stream)) {
       decl_printed = true;
       m_stream->PutCString(dest_stream.GetString());
     }
   }
 
   // if the helper failed, or there is none, do a default thing
   if (!decl_printed) {
     if (!typeName.Empty())