[clangd] Highlight structured bindings at local scope as LocalVariable

[nridge]

Fix clang-tidy warning

clang-tools-extra/clangd/SemanticHighlighting.cpp

if (isa<EnumConstantDecl>(D))
     return HighlightingKind::EnumConstant;
   if (isa<ParmVarDecl>(D))
     return HighlightingKind::Parameter;
   if (auto *VD = dyn_cast<VarDecl>(D))
     return VD->isStaticDataMember()
                ? HighlightingKind::StaticField
                : VD->isLocalVarDecl() ? HighlightingKind::LocalVariable
                                       : HighlightingKind::Variable;
-  if (isa<BindingDecl>(D))
-    return HighlightingKind::Variable;
+  if (const auto *BD = dyn_cast<BindingDecl>(D))
+    return BD->getDeclContext()->isFunctionOrMethod()
+               ? HighlightingKind::LocalVariable
+               : HighlightingKind::Variable;
   if (isa<FunctionDecl>(D))
     return HighlightingKind::Function;
   if (isa<NamespaceDecl>(D) || isa<NamespaceAliasDecl>(D) ||
       isa<UsingDirectiveDecl>(D))
     return HighlightingKind::Namespace;
   if (isa<TemplateTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
       isa<NonTypeTemplateParmDecl>(D))
     return HighlightingKind::TemplateParameter;

clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp

 $InactiveCode[[]]      #endif
     )cpp",
       R"cpp(
       struct $Class[[S]] {
         float $Field[[Value]];
         $Class[[S]] *$Field[[Next]];
       };
       $Class[[S]] $Variable[[Global]][2] = {$Class[[S]](), $Class[[S]]()};
+      auto [$Variable[[G1]], $Variable[[G2]]] = $Variable[[Global]];
       void $Function[[f]]($Class[[S]] $Parameter[[P]]) {
         int $LocalVariable[[A]][2] = {1,2};
-        auto [$Variable[[B1]], $Variable[[B2]]] = $LocalVariable[[A]];
-        auto [$Variable[[G1]], $Variable[[G2]]] = $Variable[[Global]];
-        $Class[[auto]] [$Variable[[P1]], $Variable[[P2]]] = $Parameter[[P]];
+        auto [$LocalVariable[[B1]], $LocalVariable[[B2]]] = $LocalVariable[[A]];
+        auto [$LocalVariable[[G1]], $LocalVariable[[G2]]] = $Variable[[Global]];
+        $Class[[auto]] [$LocalVariable[[P1]], $LocalVariable[[P2]]] = $Parameter[[P]];
         // Highlights references to BindingDecls.
-        $Variable[[B1]]++;
+        $LocalVariable[[B1]]++;
       }
     )cpp",
       R"cpp(
       template<class $TemplateParameter[[T]]>
       class $Class[[A]] {
         using $TemplateParameter[[TemplateParam1]] = $TemplateParameter[[T]];
         typedef $TemplateParameter[[T]] $TemplateParameter[[TemplateParam2]];
         using $Primitive[[IntType]] = int;