[lldb] Refactor OptionValueProperties to return a std::optional (NFC)

Similar to fdbe7c7faa, refactor OptionValueProperties to return a
std::optional instead of taking a fail value. This allows the caller to
handle situations where there's no value, instead of being unable to
distinguish between the absence of a value and the value happening the
match the fail value. When a fail value is required,
std::optional::value_or() provides the same functionality.

lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp

@@ -90,9 +90,9 @@ public:
   }
 
   llvm::Triple::EnvironmentType ABI() const {
-    return (llvm::Triple::EnvironmentType)
-        m_collection_sp->GetPropertyAtIndexAsEnumeration(
-            nullptr, ePropertyABI, llvm::Triple::UnknownEnvironment);
+    return (llvm::Triple::EnvironmentType)m_collection_sp
+        ->GetPropertyAtIndexAsEnumeration(nullptr, ePropertyABI)
+        .value_or(llvm::Triple::UnknownEnvironment);
   }
 
   OptionValueDictionary *ModuleABIMap() const {