[StaticAnalyzer] Use std::optional in BugReporterVisitors.cpp (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp

@@ -205,8 +205,8 @@ static bool hasVisibleUpdate(const ExplodedNode *LeftNode, SVal LeftVal,
     RLCV->getStore() == RightNode->getState()->getStore();
 }
 
-static Optional<SVal> getSValForVar(const Expr *CondVarExpr,
-                                    const ExplodedNode *N) {
+static std::optional<SVal> getSValForVar(const Expr *CondVarExpr,
+                                         const ExplodedNode *N) {
   ProgramStateRef State = N->getState();
   const LocationContext *LCtx = N->getLocationContext();
 
@@ -229,10 +229,10 @@ static Optional<SVal> getSValForVar(const Expr *CondVarExpr,
   return std::nullopt;
 }
 
-static Optional<const llvm::APSInt *>
+static std::optional<const llvm::APSInt *>
 getConcreteIntegerValue(const Expr *CondVarExpr, const ExplodedNode *N) {
 
-  if (Optional<SVal> V = getSValForVar(CondVarExpr, N))
+  if (std::optional<SVal> V = getSValForVar(CondVarExpr, N))
     if (auto CI = V->getAs<nonloc::ConcreteInt>())
       return &CI->getValue();
   return std::nullopt;
@@ -247,7 +247,7 @@ static bool isVarAnInterestingCondition(const Expr *CondVarExpr,
   if (!B->getErrorNode()->getStackFrame()->isParentOf(N->getStackFrame()))
     return false;
 
-  if (Optional<SVal> V = getSValForVar(CondVarExpr, N))
+  if (std::optional<SVal> V = getSValForVar(CondVarExpr, N))
     if (Optional<bugreporter::TrackingKind> K = B->getInterestingnessKind(*V))
       return *K == bugreporter::TrackingKind::Condition;
 
@@ -256,7 +256,7 @@ static bool isVarAnInterestingCondition(const Expr *CondVarExpr,
 
 static bool isInterestingExpr(const Expr *E, const ExplodedNode *N,
                               const PathSensitiveBugReport *B) {
-  if (Optional<SVal> V = getSValForVar(E, N))
+  if (std::optional<SVal> V = getSValForVar(E, N))
     return B->getInterestingnessKind(*V).has_value();
   return false;
 }
@@ -3244,7 +3244,7 @@ bool ConditionBRVisitor::printValue(const Expr *CondVarExpr, raw_ostream &Out,
   if (!Ty->isIntegralOrEnumerationType())
     return false;
 
-  Optional<const llvm::APSInt *> IntValue;
+  std::optional<const llvm::APSInt *> IntValue;
   if (!IsAssuming)
     IntValue = getConcreteIntegerValue(CondVarExpr, N);