LibCompress: Implement Brotli decompressor

This implements the BrotliDecompressionStream, which is a Core::Stream
that can decompress another Core::Stream.

Userland/Libraries/LibCompress/BrotliDictionary.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2022, Michiel Visser <opensource@webmichiel.nl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/ByteBuffer.h>
+
+namespace Compress {
+
+class BrotliDictionary {
+public:
+    enum TransformationOperation {
+        Identity,
+        FermentFirst,
+        FermentAll,
+        OmitFirst,
+        OmitLast,
+    };
+    struct Transformation {
+        StringView prefix;
+        TransformationOperation operation;
+        u8 operation_data;
+        StringView suffix;
+    };
+
+    static ErrorOr<ByteBuffer> lookup_word(size_t index, size_t length);
+};
+
+}