LibPDF: Draw inline images

The idea is to massage the inline image data into something that
looks like a regular image, and then use the normal image drawing code:
We translate the inline image abbreviations to the expanded version at
rendering time, then unfilter (i.e. uncompress) the image data at
rendering time, and the go down the usual image drawing path.

Normal streams are unfiltered when they're first accessed, but
inline image streams live in a page's drawing operators, and this
fits the current approach of parsing a page's operators anew
every time the page is rendered.

(We also need to add some special-case handling for color spaces
of inline images: Inline images can use named color spaces, while
regular images always use direct color space objects.)

Userland/Libraries/LibPDF/Document.h

@@ -156,6 +156,8 @@ public:
 
     PDFErrorOr<Vector<DeprecatedFlyString>> read_filters(NonnullRefPtr<DictObject>);
 
+    PDFErrorOr<void> unfilter_stream(NonnullRefPtr<StreamObject> stream) { return m_parser->unfilter_stream(move(stream)); }
+
 private:
     explicit Document(NonnullRefPtr<DocumentParser> const& parser);