[clangd] Dont display `<unknown>` kinds in hover board

Summary:
Currently when hovering over an `auto` or `decltype` that resolve to a
builtin-type, clangd would display `<unknown>` as the kind of the symbol.

Drop that to make rendering nicer.

Reviewers: usaxena95

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D72777

clang-tools-extra/clangd/Hover.cpp

@@ -522,7 +522,8 @@ markup::Document HoverInfo::present() const {
   // level 1 and 2 headers in a huge font, see
   // https://github.com/microsoft/vscode/issues/88417 for details.
   markup::Paragraph &Header = Output.addHeading(3);
-  Header.appendText(index::getSymbolKindString(Kind));
+  if (Kind != index::SymbolKind::Unknown)
+    Header.appendText(index::getSymbolKindString(Kind));
   assert(!Name.empty() && "hover triggered on a nameless symbol");
   Header.appendCode(Name);
 

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

@@ -1655,7 +1655,7 @@ TEST(Hover, Present) {
             HI.Kind = index::SymbolKind::Unknown;
             HI.Name = "X";
           },
-          R"(<unknown> X)",
+          R"(X)",
       },
       {
           [](HoverInfo &HI) {