LibMarkdown: Add blockquotes

Userland/Libraries/LibMarkdown/BlockQuote.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021, Peter Elliott <pelliott@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/OwnPtr.h>
+#include <LibMarkdown/Block.h>
+#include <LibMarkdown/ContainerBlock.h>
+
+namespace Markdown {
+
+class BlockQuote final : public Block {
+public:
+    BlockQuote(OwnPtr<ContainerBlock> contents)
+        : m_contents(move(contents))
+    {
+    }
+    virtual ~BlockQuote() override { }
+
+    virtual String render_to_html(bool tight = false) const override;
+    virtual String render_for_terminal(size_t view_width = 0) const override;
+
+    static OwnPtr<BlockQuote> parse(LineIterator& lines);
+
+private:
+    OwnPtr<ContainerBlock> m_contents;
+};
+
+}