[wpiutil] Replace LLVM StringMap impl with std::map

As string_view operations on std::map<std::string> won't be integrated
until C++26, placeholder implementations are used which are less efficient
in a couple of situations (e.g. insert with hint).

wpilibc/src/main/native/cpp/Tracer.cpp

@@ -49,8 +49,8 @@ void Tracer::PrintEpochs(wpi::raw_ostream& os) {
     m_lastEpochsPrintTime = now;
     for (const auto& epoch : m_epochs) {
       os << fmt::format(
-          "\t{}: {:.6f}s\n", epoch.getKey(),
-          duration_cast<microseconds>(epoch.getValue()).count() / 1.0e6);
+          "\t{}: {:.6f}s\n", epoch.first,
+          duration_cast<microseconds>(epoch.second).count() / 1.0e6);
     }
   }
 }

wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardComponentBase.cpp

@@ -46,7 +46,7 @@ void ShuffleboardComponentBase::BuildMetadata(
   if (GetProperties().size() > 0) {
     auto propTable = metaTable->GetSubTable("Properties");
     for (auto& entry : GetProperties()) {
-      propTable->GetEntry(entry.first()).SetValue(entry.second);
+      propTable->GetEntry(entry.first).SetValue(entry.second);
     }
   }
   m_metadataDirty = false;

wpilibc/src/main/native/cpp/smartdashboard/Mechanism2d.cpp

@@ -51,7 +51,7 @@ void Mechanism2d::InitSendable(nt::NTSendableBuilder& builder) {
   m_colorPub = m_table->GetStringTopic(kBackgroundColor).Publish();
   m_colorPub.Set(m_color);
   for (const auto& entry : m_roots) {
-    const auto& root = entry.getValue().get();
-    root->Update(m_table->GetSubTable(entry.getKey()));
+    const auto& root = entry.second.get();
+    root->Update(m_table->GetSubTable(entry.first));
   }
 }

wpilibc/src/main/native/cpp/smartdashboard/MechanismObject2d.cpp

@@ -18,8 +18,7 @@ void MechanismObject2d::Update(std::shared_ptr<nt::NetworkTable> table) {
   std::scoped_lock lock(m_mutex);
   m_table = table;
   UpdateEntries(m_table);
-  for (const wpi::StringMapEntry<std::unique_ptr<MechanismObject2d>>& entry :
-       m_objects) {
-    entry.getValue()->Update(m_table->GetSubTable(entry.getKey()));
+  for (const auto& entry : m_objects) {
+    entry.second->Update(m_table->GetSubTable(entry.first));
   }
 }

wpilibc/src/main/native/cpp/smartdashboard/SmartDashboard.cpp

@@ -126,7 +126,7 @@ wpi::Sendable* SmartDashboard::GetData(std::string_view key) {
   if (it == inst.tablesToData.end()) {
     throw FRC_MakeError(err::SmartDashboardMissingKey, "{}", key);
   }
-  return wpi::SendableRegistry::GetSendable(it->getValue());
+  return wpi::SendableRegistry::GetSendable(it->second);
 }
 
 bool SmartDashboard::PutBoolean(std::string_view keyName, bool value) {
@@ -254,6 +254,6 @@ void SmartDashboard::UpdateValues() {
   inst.listenerExecutor.RunListenerTasks();
   std::scoped_lock lock(inst.tablesToDataMutex);
   for (auto& i : inst.tablesToData) {
-    wpi::SendableRegistry::Update(i.getValue());
+    wpi::SendableRegistry::Update(i.second);
   }
 }

wpilibc/src/main/native/include/frc/smartdashboard/SendableChooser.h

@@ -49,7 +49,7 @@ class SendableChooser : public SendableChooserBase {
   }
 
  public:
-  using CopyType = decltype(_unwrap_smart_ptr(m_choices.lookup("")));
+  using CopyType = decltype(_unwrap_smart_ptr(m_choices.find("")->second));
 
   SendableChooser() = default;
   ~SendableChooser() override = default;
@@ -105,7 +105,11 @@ class SendableChooser : public SendableChooserBase {
     if (selected.empty()) {
       return CopyType{};
     } else {
-      return _unwrap_smart_ptr(m_choices.lookup(selected));
+      auto it = m_choices.find(selected);
+      if (it == m_choices.end()) {
+        return CopyType{};
+      }
+      return _unwrap_smart_ptr(it->second);
     }
   }
 
@@ -128,13 +132,8 @@ class SendableChooser : public SendableChooserBase {
         [=, this] {
           std::vector<std::string> keys;
           for (const auto& choice : m_choices) {
-            keys.emplace_back(choice.first());
+            keys.emplace_back(choice.first);
           }
-
-          // Unlike std::map, wpi::StringMap elements
-          // are not sorted
-          std::sort(keys.begin(), keys.end());
-
           return keys;
         },
         nullptr);