[clang-tools-extra] [clang-doc] Add Markdown AST node type definitions (PR #205609)

[Neil Nair via cfe-commits]

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@@ -0,0 +1,73 @@
+#include "support/Markdown.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
+#include "gtest/gtest.h"
+
+using namespace clang::doc::markdown;
+using namespace llvm;
+
+namespace {
+
+TEST(MarkdownNodeTest, TextNode) {
+  BumpPtrAllocator Arena;
+  auto *N = new (Arena) TextNode("hello");
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Neil-N4 wrote:

Simplified to stack construction instead

https://github.com/llvm/llvm-project/pull/205609