LibCompress: Move `CanonicalCode` in the `Brotli` namespace

The class was an inner class of `BrotliDecompressionStream`, let's move
it outside the `Stream` object in order to ease the access to user only
interested in this part.

Userland/Libraries/LibCompress/Brotli.cpp

@@ -11,7 +11,7 @@
 
 namespace Compress {
 
-ErrorOr<size_t> BrotliDecompressionStream::CanonicalCode::read_symbol(LittleEndianInputBitStream& input_stream) const
+ErrorOr<size_t> Brotli::CanonicalCode::read_symbol(LittleEndianInputBitStream& input_stream) const
 {
     size_t code_bits = 1;
 
@@ -137,7 +137,7 @@ ErrorOr<size_t> BrotliDecompressionStream::read_variable_length()
     }
 }
 
-ErrorOr<size_t> BrotliDecompressionStream::CanonicalCode::read_complex_prefix_code_length(LittleEndianInputBitStream& stream)
+ErrorOr<size_t> Brotli::CanonicalCode::read_complex_prefix_code_length(LittleEndianInputBitStream& stream)
 {
     // Symbol   Code
     // ------   ----
@@ -171,7 +171,7 @@ ErrorOr<size_t> BrotliDecompressionStream::CanonicalCode::read_complex_prefix_co
     }
 }
 
-ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::CanonicalCode::read_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size)
+ErrorOr<Brotli::CanonicalCode> Brotli::CanonicalCode::read_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size)
 {
     size_t hskip = TRY(stream.read_bits(2));
 
@@ -181,7 +181,7 @@ ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::Can
     return TRY(read_complex_prefix_code(stream, alphabet_size, hskip));
 }
 
-ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::CanonicalCode::read_simple_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size)
+ErrorOr<Brotli::CanonicalCode> Brotli::CanonicalCode::read_simple_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size)
 {
     CanonicalCode code {};
 
@@ -230,7 +230,7 @@ ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::Can
     return code;
 }
 
-ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::CanonicalCode::read_complex_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size, size_t hskip)
+ErrorOr<Brotli::CanonicalCode> Brotli::CanonicalCode::read_complex_prefix_code(LittleEndianInputBitStream& stream, size_t alphabet_size, size_t hskip)
 {
     // hskip should only be 0, 2 or 3
     VERIFY(hskip != 1);
@@ -259,7 +259,7 @@ ErrorOr<BrotliDecompressionStream::CanonicalCode> BrotliDecompressionStream::Can
             return Error::from_string_literal("invalid prefix code");
     }
 
-    BrotliDecompressionStream::CanonicalCode temp_code;
+    CanonicalCode temp_code;
     if (number_of_non_zero_symbols > 1) {
         size_t code_value = 0;
         for (size_t bits = 1; bits <= 5; bits++) {

Userland/Libraries/LibCompress/Brotli.h

@@ -13,7 +13,35 @@
 
 namespace Compress {
 
+namespace Brotli {
+
+class CanonicalCode {
+public:
+    CanonicalCode() = default;
+
+    static ErrorOr<CanonicalCode> read_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size);
+    static ErrorOr<CanonicalCode> read_simple_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size);
+    static ErrorOr<CanonicalCode> read_complex_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size, size_t hskip);
+
+    ErrorOr<size_t> read_symbol(LittleEndianInputBitStream&) const;
+    void clear()
+    {
+        m_symbol_codes.clear();
+        m_symbol_values.clear();
+    }
+
+private:
+    static ErrorOr<size_t> read_complex_prefix_code_length(LittleEndianInputBitStream&);
+
+    Vector<size_t> m_symbol_codes;
+    Vector<size_t> m_symbol_values;
+};
+
+}
+
 class BrotliDecompressionStream : public Stream {
+    using CanonicalCode = Brotli::CanonicalCode;
+
 public:
     enum class State {
         WindowSize,
@@ -26,28 +54,6 @@ public:
         CompressedDictionary,
     };
 
-    class CanonicalCode {
-    public:
-        CanonicalCode() = default;
-
-        static ErrorOr<CanonicalCode> read_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size);
-        static ErrorOr<CanonicalCode> read_simple_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size);
-        static ErrorOr<CanonicalCode> read_complex_prefix_code(LittleEndianInputBitStream&, size_t alphabet_size, size_t hskip);
-
-        ErrorOr<size_t> read_symbol(LittleEndianInputBitStream&) const;
-        void clear()
-        {
-            m_symbol_codes.clear();
-            m_symbol_values.clear();
-        }
-
-    private:
-        static ErrorOr<size_t> read_complex_prefix_code_length(LittleEndianInputBitStream&);
-
-        Vector<size_t> m_symbol_codes;
-        Vector<size_t> m_symbol_values;
-    };
-
     struct Block {
         size_t type;
         size_t type_previous;